chat: add Configure Tools CodeLens for .toolsets.jsonc

[jamesmontemagno]

Request

Add Configure Tools CodeLens support when editing .toolsets.jsonc.

Desired behavior

• Show Configure Tools CodeLens for tool set definitions in .toolsets.jsonc.
• Reuse existing tools picker UX.
• Persist selected tools back into the tool set ools array.

Why this matters

• Improves discoverability and consistency with other tool configuration flows.
• Reduces manual JSON editing and syntax errors.
• Speeds up authoring and maintenance of tool sets.

Notes

CodeLens should behave correctly with refs/qualified names and preserve stable serialization semantics.

[jamesmontemagno]

Fixed in : #320486

[jamesmontemagno]

@aeschli can be close when ready now that merged