Add RidSpecific, Make Apps RID Specific By Default & RID Now FDD By Default in 8.0+

[nagilson]

For #26031
7.0 backport #28376

Adds RuntimeSpecific:

1. Makes TFM >= 8.0 Exe apps Infer RID automatically (FDD)
2. RIDS no longer imply Self-Contained for TFM >= 8.0
3. Allows opt out of the inferred RID behavior (FDDefault) by setting RuntimeSpecific to false, but no opt-out to not implying SC with RIDs in TFM 8.0
4. Warns for apps that didn't set SC but set RIDs in TFM < 8 that they need to set SC explicitly to get the same behavior with TFM 8.0. Warning will go away after SC is set, either to true or false.

Based on .NET 8.0 Breaking Changes Notes:

• Make RID Specific Apps FDD (NOT SC) by default instead of SC
• Make EXE Apps Rid Specific By Default

Tested Behavior:

• RidNoLongerImpliesSelfContainedForTFMOverSeven
• RidImpliesSelfContainedButWarnsIfNotSetForTFMUnderEight
• RidSpecificMakesExecutableAppsAboveTFMSevenRidSpecificByDefault
• RidSpecificAllowsOptOutRIDlessAppsOnExecutableAppsForTFMAboveSeven
• SelfContainedPlusRuntimeIdentifierDoesNotTriggerEightTFMFDDBreakingChangeWarning
• RuntimeIdentifiersDisablesRuntimeSpecificFDDBehavior

Questions:

• Why does TargetFrameworkInference sometimes not run? I accounted for that, but don't understand the contexts.
• Do we care to set a rid with RidSpecific by default if RuntimeIdentifiers is set? ATM, I made it so RuntimeSpecific doesn't do anything if RuntimeIdentifiers is set, nor will apps with RuntimeIdentifiers be FDD.
• Could we use a more specific RID?

Verify:
Make sure you can still specify -r runtime without it being overriden.
Make sure you can still specify self-contained to true even if you do /p:SelfContained=true.

[nagilson]

Still blocked by #28563

[nagilson]

This is no longer blocked.

[teo-tsirpanis]

Suggested change

	<PropertyGroup Condition="'$(RuntimeSpecific)' == '' and '$(_TargetFrameworkVersionWithoutV)' != '' and '$(_TargetFrameworkVersionWithoutV)' >= '8.0' and '$(OutputType)' == 'Exe'">
	<PropertyGroup Condition="'$(RuntimeSpecific)' == '' and '$(_TargetFrameworkVersionWithoutV)' != '' and '$(_TargetFrameworkVersionWithoutV)' >= '8.0' and ('$(OutputType)' == 'Exe' or '$(OutputType)' == 'WinExe')">

[nagilson]

We aren't doing this proposal anymore, there is a new proposal

[teo-tsirpanis]

Where is that new proposal?

[nagilson]

#29950 (comment)