Fix edit tools for headless tool invocation (scenario automation)

[rwoll]

Fix edit tools for headless tool invocation (scenario automation)

Edit tools (apply_patch, create_file, replace_string) fail when invoked
via vscode.lm.invokeTool() outside a chat participant context because
resolveInput() is never called and this._promptContext?.stream is undefined.

This unblocks the vscode-copilot-evaluation tool call service mode where an
external process invokes tools via HTTP without a VS Code chat session.

Changes

For each tool, when no chat response stream is available (!hasStream):

• apply_patch: Apply the already-built WorkspaceEdit directly via
  workspaceService.applyEdit() instead of streaming through responseStream
• create_file: Write file directly via fileSystemService.writeFile()
• replace_string: Build a WorkspaceEdit from the generated text edits
  and apply directly

The existing stream-based code path is completely unchanged. The !hasStream
branches return early before any stream code is reached.

Files Changed

File	What Changes
src/extension/tools/node/applyPatchTool.tsx	Remove stream requirement from guard; add !hasStream block that applies WorkspaceEdit directly
src/extension/tools/node/createFileTool.tsx	Remove stream requirement from guard; add !hasStream block that writes file via fileSystemService
src/extension/tools/node/abstractReplaceStringTool.tsx	Remove stream requirement from guard; add WorkspaceEdit import; add !hasStream block that applies text edits directly; remove overly-restrictive _promptContext check from input validation

Tests

Added 5 new headless-mode tests across 3 test files:

• applyPatch.spec.tsx: ADD file and UPDATE file patches without stream
• createFileTool.spec.ts (new): Create file and empty file without stream
• replaceStringTool.spec.tsx: Replace string without stream

What's NOT changed

• insertEditTool.tsx — requires VS Code core changes, only used by older/smaller models
• The stream path — untouched, !hasStream blocks return early before any stream code
• resolveInput() — unchanged, simply never called in automation mode

Fixes microsoft/vscode-copilot-evaluation#2818