Remove unnecessary types/vscode (fix build issue)

[jmcphers]

Addresses this build issue:

[17:44:35] Error: @types/vscode ^1.73.0 greater than engines.vscode ^1.65.0. Consider upgrade engines.vscode or use an older @types/vscode version
    at validateVSCodeTypesCompatibility (/Users/jmcphers/git/positron/build/node_modules/@vscode/vsce/out/validation.js:115:19)
    at validateManifest (/Users/jmcphers/git/positron/build/node_modules/@vscode/vsce/out/package.js:913:59)
    at async Promise.all (index 0)
    at async listFiles (/Users/jmcphers/git/positron/build/node_modules/@vscode/vsce/out/package.js:1333:22)

The fix is to remove @types/vscode from positron-assistant and get these types from Positron's internal copy instead.

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical

^{readme  valid tags}