Integration tests to create for the extension

[aeisenberg]

Once #645, we will have the option of adding integration tests to the extension. This issue will keep a list of all the integration tests we want to create. And over time, we will implement all:

• [ ] AST Viewer works and displays some results
• Run Queries
  • [ ] Can run a query without crashing
  • [ ] Query can run and create a results web view that displays results
  • [ ] Can run a simple query and results are produced See https://github.com/github/vscode-codeql/pull/694#discussion_r532939540
• [ ] View DIL
• [ ] View Logs
• databases
  • [ ] Add from folder
  • [x] Add from archive
  • [x] Add from LGTM
  • [x] Add from URL
  • [ ] Remove from folder
  • [ ] Remove from archive
  • [ ] Remove from LGTM
  • [ ] Remove from URL
  • [ ] Also, test that the language is correctly guessed
• [ ] Compare queries shows some results

This is a continuation of #642.

[aeisenberg]

Uploading a simple database for use in integration tests. This database zip file should not be removed.

simple-db.zip