Clean up RewrittenSyntaxTree naming and null handling in DefaultTagHe…

…lperResolutionPhase (#13003)

* Clean up RewrittenSyntaxTree naming and null handling in resolution phase
- Remove syntax tree access from DefaultTagHelperResolutionPhase.ExecuteCore;
  use codeDocument.ParserOptions directly instead of syntaxTree?.Options
- Fix null handling: parserOptions was potentially null when no syntax tree
  was present; codeDocument.ParserOptions is always non-null
- Remove unused ParserOptions field from ResolutionContext struct
- Add clarifying comment explaining why options are read from the document

* Rename GetPreTagHelperSyntaxTree→GetSyntaxTree and GetSyntaxTree→GetTagHelperRewrittenSyntaxTree

- Rename RazorCodeDocument fields and all related methods:
  - _preTagHelperSyntaxTree → _syntaxTree (canonical, pre-rewrite tree)
  - _syntaxTree → _tagHelperRewrittenSyntaxTree (rewritten tree)
- Update all phase code:
  - DefaultRazorParsingPhase: WithSyntaxTree → WithTagHelperRewrittenSyntaxTree
  - DefaultRazorSyntaxTreePhase: same rename
  - DefaultRazorTagHelperContextDiscoveryPhase: update fallback + early return
  - DefaultRazorIntermediateNodeLoweringPhase: remove fallback (uses GetSyntaxTree())
  - DefaultRazorTagHelperRewritePhase: TryGetSyntaxTree + WithTagHelperRewrittenSyntaxTree
  - SourceGeneratorProjectEngine: WithSyntaxTree(GetRequiredTagHelperRewrittenSyntaxTree())
- Update all workspaces production code to GetTagHelperRewrittenSyntaxTree
- Update all test files to use correct methods

* Fix tests to use GetSyntaxTree()/WithSyntaxTree() and eliminate fallback in discovery phase

- DefaultRazorParsingPhase: sets _syntaxTree (canonical) directly, not _tagHelperRewrittenSyntaxTree
- DefaultRazorSyntaxTreePhase: reads/writes _syntaxTree (canonical)
- DefaultRazorTagHelperContextDiscoveryPhase: reads _syntaxTree directly (no fallback needed since parsing always sets it); also removes redundant WithSyntaxTree(syntaxTree) write and simplifies early return
- SourceGeneratorProjectEngine: remove redundant WithSyntaxTree() pre-discovery call (parsing now sets it)
- NamespaceComputer: TryGetTagHelperRewrittenSyntaxTree → TryGetSyntaxTree
- Compiler-layer tests: all non-rewrite tests switch to GetSyntaxTree()/WithSyntaxTree()
- Execute_CombinesErrorsOnRewritingErrors: keeps GetTagHelperRewrittenSyntaxTree() (tests rewrite output)
- IntegrationTestBase/RazorBaselineIntegrationTestBase: use GetTagHelperRewrittenSyntaxTree() ?? GetRequiredSyntaxTree() fallback for AssertSourceMappingsMatchBaseline/AssertLinePragmas
- RazorCodeDocumentExtensionsTest: WithSyntaxTree (matches NamespaceComputer using TryGetSyntaxTree)

Localized file check-in by OneLocBuild Task: Build definition ID 262:…

… Build ID 2943270 (#13009)

Localized file check-in by OneLocBuild Task: Build definition ID 262:…

… Build ID 2943270 (#13009)

Remove the UseCache property and old benchmark (#12962)

I _SWEAR_ I pushed a commit that did this before I merged my other PR,
but either GitHub was having issues, or I was in a fugue state

Remove the UseCache property and old benchmark (#12962)

I _SWEAR_ I pushed a commit that did this before I merged my other PR,
but either GitHub was having issues, or I was in a fugue state

Remove the old language server (#12871)

Fixes #12491

There is still a few things we can clean up after this, but this makes
the Find All Refs results make a lot more sense.

I suspect commit-at-a-time makes the most sense for this one, but who
knows whether GitHub will do a good job of showing diffs.

Val build:
https://dev.azure.com/dnceng/internal/_build/results?buildId=2919555&view=results
Test insertion:
https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/715049

Remove LegacyEditor projects (#12869)

Step 1 of many.

Test insertion is green(ish):
https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/714698

Remove LegacyEditor projects (#12869)

Step 1 of many.

Test insertion is green(ish):
https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/714698

Remove LegacyEditor projects (#12869)

Step 1 of many.

Test insertion is green(ish):
https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/714698

Remove LegacyEditor projects (#12869)

Step 1 of many.

Test insertion is green(ish):
https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/714698