Fix #32541: toggle block comment when cursor is inside comment

[amartin217]

Fix #32541: Toggle block comment from inside comment block

Summary:
Improves editor.action.blockComment so that when the cursor is inside an existing block comment with no selection, the command will remove the surrounding block comment instead of inserting a new one.

Changes:

• Detects when the cursor is inside a block comment using language configuration
• If collapsed selection is inside a block comment, removes the full block comment range
• Preserves existing behavior for selections, multi-cursor edits, and non-commented code

Why:
Makes block comment toggling more intuitive by allowing users to toggle comments without manually selecting the entire block, matching behavior in other editors.

Notes:
-Language-aware (no hardcoded comment tokens)
-No changes to line comment behavior or selection-based toggling

[amartin217]

@microsoft-github-policy-service agree