Support refreshing MCP tool, resources, etc lists and avoid prompts

[lambertjosh]

Vibe coded, tested but not reviewed at a code level, in draft. This PR attempts to do two things:

1. Remove the annoying MCP tool change notifications that appear on extension init and provider changes.
2. Support refreshing the MCP cache when an MCP server informs it that tools/resource/etc lists have changed.

The primary importance IMO is hiding the notifications by properly handling them. The bonus is improvement support for MCP, as there is a risk that these tool lists could change after initial load and this better supports that.

Here is the offending notifications:

[changeset-bot]

⚠️ No Changeset found

Latest commit: 5bf67b6

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR