Change the way raw values are preserved in TryParse

[nkolev92]

Bug

Related: NuGet/Home#12728

Description

Say we have the lib/{tfm}/{assembly} pattern
During the TokenSegment.TryParse method if we encounter a tfm, we store the parsed tfm value in the ContentItem to pick the best group later. We also store the tfm_raw in some cases, since we need it in pack. Now since this is only needed during pack, we don't need to store and create string allocations during restore.

The implementation isn't a design I love, but something that we're constrained to due to our public APIs. Open to other suggestions if people have any.
In general server team and SDK team would use the ManagedCodeConventions specified by default and used during restore. In order to not break that, I removed tfm_raw allocations completely in the general codepath.
A PatternDefintion carries the knowledge that the parser needs to preserve the raw values. I added it as an init property to avoid breaking the constructor or a lot of code duplication. The fact that it's an init property keeps it immutable.
As part of this work, I also null annotated ContentQueryDefinition and improved the allocations in the constructor. This saves only few hundred KBs so it wasn't worth calling out.

Total, this shaves off about 10MB during an OrchardCore restore.

Before:

Name                                                                                                                                                                                                                     	Inc %	          Inc
 nuget.packaging!NuGet.ContentModel.Infrastructure.PatternExpression+TokenSegment.TryMatch(class NuGet.ContentModel.ContentItem&,class System.String,class System.Collections.Generic.IReadOnlyDictionary`2,int32,int32&)	  0.9	   79,744,304
+ mscorlib.ni!System.Collections.Generic.Dictionary`2[System.__Canon,System.__Canon].Insert(System.__Canon, System.__Canon, Boolean)                                                                                     	  0.4	   33,491,856
+ nuget.packaging!NuGet.ContentModel.ContentItem.get_Properties()                                                                                                                                                        	  0.2	   17,589,200
+ nuget.packaging!ContentPropertyDefinition.TryLookup                                                                                                                                                                    	  0.1	   12,173,224
+ system.memory.ni!?                                                                                                                                                                                                     	  0.1	    9,595,200
+ clr!JIT_New                                                                                                                                                                                                            	  0.1	    6,894,824

After:

Name                                                                                                                                                                                                                     	Inc %	          Inc
 nuget.packaging!NuGet.ContentModel.Infrastructure.PatternExpression+TokenSegment.TryMatch(class NuGet.ContentModel.ContentItem&,class System.String,class System.Collections.Generic.IReadOnlyDictionary`2,int32,int32&)	  0.8	   69,501,008
+ mscorlib.ni!System.Collections.Generic.Dictionary`2[System.__Canon,System.__Canon].Insert(System.__Canon, System.__Canon, Boolean)                                                                                     	  0.4	   32,375,832
+ nuget.packaging!NuGet.ContentModel.ContentItem.get_Properties()                                                                                                                                                        	  0.2	   19,186,544
+ nuget.packaging!ContentPropertyDefinition.TryLookup                                                                                                                                                                    	  0.1	   10,983,648
+ clr!JIT_New                                                                                                                                                                                                            	  0.1	    6,954,984

Note that this removes: + system.memory.ni? which is the string actualization from ReadOnlyMemory in the specific TryMatch method.
After I think the only realistic allocation reductions that don't completely involve refactoring all of the assets selection are the dictionary usages.

Some micro benchmarks. The improvements are more significant there.

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
NJ	44.65 us	0.257 us	0.228 us	3.9673	0.1221	67.56 KB
MicrosoftBuildRuntime	66.93 us	0.243 us	0.228 us	8.4229	0.7324	141.95 KB
AllPackages	165,097.44 us	1,003.022 us	889.153 us	16000.0000	2250.0000	272144.95 KB

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
NJ	40.24 us	0.353 us	0.331 us	3.2959	0.1221	56.5 KB
MicrosoftBuildRuntime	62.62 us	0.822 us	0.686 us	8.1787	0.6104	138.23 KB
AllPackages	152,979.21 us	804.331 us	713.019 us	14250.0000	2000.0000	240733.08 KB

PR Checklist

• Meaningful title, helpful description and a linked NuGet/Home issue
• Added tests Tests exist.
• Link to an issue or pull request to update docs if this PR changes settings, environment variables, new feature, etc.

[nkolev92]

@NuGet/nuget-client Can I please get a review here?

I have 2 follow-up PRs and they're both dependent on this one.

[zivkan]

public APIs 🤦

[nkolev92]

@martinrrm If you have more feedback, I'd be happy to address it.
I'm just trying to unblock my other 2 PRs.