feat(scope-zone): new scope manager to support async operations in web

[obecny]

Which problem is this PR solving?

1. Fixes Add new ZoneScopeManager for web #435

Short description of the changes

This PR adds new ZoneScopeManager for web that will support async operation - will keep the reference to scope (span) between asynchronous operations. This will allow to build more plugins for web. It is created into 2 packages. One is bundled together with zone.js and second allows to use your own zone.js if user already has it (for example when building angular apps)

Updated the corresponding readme too.

[obecny]

cc @draffensperger

[codecov-io]

Codecov Report

Merging #461 into master will decrease coverage by 1.96%.
The diff coverage is 28.51%.

@@            Coverage Diff             @@
##           master     #461      +/-   ##
==========================================
- Coverage   94.39%   92.43%   -1.97%     
==========================================
  Files         120      143      +23     
  Lines        5749     6863    +1114     
  Branches      533      597      +64     
==========================================
+ Hits         5427     6344     +917     
- Misses        322      519     +197

Impacted Files	Coverage Δ
...entelemetry-scope-zone-peer-dep/test/utils.test.ts	0% <0%> (ø)
packages/opentelemetry-web/test/WebTracer.test.ts	0% <0%> (ø)	⬆️
...-scope-zone-peer-dep/test/ZoneScopeManager.test.ts	0% <0%> (ø)
...ages/opentelemetry-scope-zone-peer-dep/src/util.ts	100% <100%> (ø)
...emetry-scope-zone-peer-dep/src/ZoneScopeManager.ts	87.95% <87.95%> (ø)
...kages/opentelemetry-metrics/test/mocks/Exporter.ts	66.66% <0%> (-33.34%)	⬇️
...es/opentelemetry-node/src/instrumentation/utils.ts	90.47% <0%> (-9.53%)	⬇️
...entelemetry-exporter-jaeger/test/transform.test.ts	100% <0%> (ø)	⬆️
.../opentelemetry-plugin-dns/test/utils/assertSpan.ts	100% <0%> (ø)	⬆️
...try-node/test/instrumentation/PluginLoader.test.ts	100% <0%> (ø)	⬆️
... and 28 more

[draffensperger]

This is really cool! I've given a first pass that caught mostly extra log entries, style changes, etc.

I'd like to understand and review the design and core code a bit more carefully though.

Could you provide a longer-form JSDoc comment at the start of the zone scope manager that explains its design at a high level, including what data it stores, how it attaches / unattaches to listeners and timeouts, etc.?

I'm also curious as to why the extra complexity with binding is needed vs. relying more heavily on Zones themselves (i.e. delegating the binding to the Zone binding functions)

[draffensperger]

Awesome that this now supports parallel async operations. I think this is really coming together.

I made some nit-picky type comments, but also asked a question about the event listeners - I'd like to understand that part better and help us think through whether it's needed.

[draffensperger]

Nice work on this @obecny !! I think this is in a good place to merge in.

[mayurkale22]

LGTM 👍