[Enhancement] Expose extract-refresh, schedule & governance data in Tableau MCP

[HannahHernalinHF]

Summary

The Tableau MCP tools currently return content metadata (name, owner, tags,
workbook updatedAt) but not the refresh/schedule/governance data that's
visible in the Tableau UI. Requesting new tools (or extended responses) to
expose the following via the Tableau REST API v3.19.

Requested capabilities

1. Extract last refresh time – extractLastRefreshTime / extractLastUpdateTime
   (from GET /sites/{site}/datasources/{id})
2. Refresh schedules + suspended state – GET /sites/{site}/tasks/extractRefreshes
3. Refresh job status / failure counts – GET /sites/{site}/jobs?jobType=RefreshExtract
   (to detect failed / suspended-after-N-tries)
4. Workbook → datasource mapping – GET /sites/{site}/workbooks/{id}/connections
   (to flag weakest-link stale extracts, e.g. 4/5 fresh, 1 stale)
5. PII / sensitivity labels – data quality warnings / labels API

Use case

Build a per-dashboard health report showing last refresh time, schedule,
failed refreshes, stale extracts, and PII flags — currently blocked because
these fields aren't wrapped by the MCP.

Notes

• Per the automatic support answer, the service PAT currently uses a Viewer
  role. Some of the above (jobs/schedules) may require elevated permissions —
  flagging so it can be scoped.
• Priority if phased: @W-18465161: Enable server logging capability #1 first, then Welcome to tableau-mcp Discussions! #3 and @W-18465174: Add unit test framework and some basic unit tests #4.