ocioview updates & fixes

[michdolan]

This PR makes a number of updates and improvements to ocioview:

• When closing the application or creating a new config, users will now only be prompted to save their config if changes have been made. Previously the initial application state would be detected as a modified config. Note: config modification detection is limited to the data included in the config's cache ID, which does not currently include the config's name or description.
• Per suggestion from @KelSolaar in ocioview image and PySide6 updates #1912 , changed the message router interface to use properties instead of getters and setters.
• Added a warning when loading a config that contains a view definition that references a view transform and non-display color space, which results in that view being interpreted as a OCIO v1 style view, dropping the view transform. Technically OCIO supports a view with a view transform and a scene reference color space, but in ocioview we intentionally limit color space selection to display color spaces when using a view transform.
• Improved consistency of icon sizing throughout application, and improved pixmap transformation quality for consistent icon filtering across tabs, buttons, and items.
• Added ProcessorContext interface to reference input and output processor parameters so application components that receive a viewer's processor can inspect the config items that created it. This dataclass includes the processor's: input color space name, output transform item type, output transform item name, and transform direction. This should resolve questions raised in PR: ocioview - Chromaticities Inspector #1914 .

[KelSolaar]

Feels a bit "magical" :)

Might need a dedicated definition in the future to manage all those comparisons if we need to do it elsewhere.

[KelSolaar]

I was talking about this block specifically:

                isinstance(msg_raw, tuple)
                and len(msg_raw) == 2
                and isinstance(msg_raw[0], ProcessorContext)
                and isinstance(msg_raw[1], ocio.Processor)

[KelSolaar]

Thanks @michdolan, LGTM!