Change corelib to resx, strongly typed resources, and split resources for \shared

[danmoseley]

We need to

• Change from .txt to .resx
• Change to use SR.cs generated from .resx instead of GetResourceString("..")
• Split the resx into two pieces, one in \shared\ that contains every string used in at least one place in any code in \shared\, and another outside of \shared\ that contains all the other strings.
• Do the same split in CoreRT
• Enabling syncing for .resx files if it isn't already

@alexperovich this is just to track what we already discussed.

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Issue Details

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We need to

• Change from .txt to .resx
• Change to use SR.cs generated from .resx instead of GetResourceString("..")
• Split the resx into two pieces, one in \shared\ that contains every string used in at least one place in any code in \shared\, and another outside of \shared\ that contains all the other strings.
• Do the same split in CoreRT
• Enabling syncing for .resx files if it isn't already

@alexperovich this is just to track what we already discussed.

Author:	danmosemsft
Assignees:	-
Labels:	area-Infrastructure-coreclr, linkable-framework, up-for-grabs
Milestone:	Future

[MichalStrehovsky]

Bumping this to .NET 6 since this means that Mono CoreLib builds carry junk CoreCLR resource strings. #2151 made Mono just use the same RESX file as CoreCLR instead of doing a proper split.

[akoeplinger]

@MichalStrehovsky I took a stab at this but realized that since we run the trimmer during the libraries build we end up stripping away the unused resources (edit only the properties, not the embedded resources). Do you still think it's worth doing the .resx file split?