[tools sets] support qualified names

[charris-msft]

Version: 1.106.0-insider (user setup)
Commit: f030344
Date: 2025-10-15T05:02:11.625Z
Electron: 37.6.0
ElectronBuildId: 12506819
Chromium: 138.0.7204.251
Node.js: 22.19.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26200

Steps to Reproduce:

1. Create a list of tools using a chat mode (because it has the UX to do it) including built-in, github, azure mcp, etc. tools.
2. Copy/paste the list of tools into a toolset
3. Add the toolset to a chat session and see that tools from github and azure MCP servers are not included.

Example:
MyZavaTools.toolsets.jsonc

[aeschli]

Yes, tool-sets didn't get any love lately and still use the unqualified tool names. Makes sense to make this consistent.