Query Experience - Validate Query

[mihirwagleMSFT]

Issue: Add validate_query tool

Labels: enhancement, query-experience, priority:high

Problem:
M code syntax errors only surface at execution time. Wasted round trips for typos and malformed queries.

Proposed Solution:
Syntax validation tool that checks M code without executing it.

Acceptance Criteria:

• Tool accepts: M code string
• Returns success or error with line number and message
• Fast response (no data source connection needed for syntax check)