* Allow the codeql-action to be run locally

This change allows the codeql-action to be run locally through
[act](https://github.com/nektos/act).

In order to run the action locally, you need to do two things:

1. Add the `CODEQL_LOCAL_RUN: true` environment variable. The only way
   I could figure out how to do this was to add it directly in the
   workflow file in an `env` block. It _should_ be possible to add it
   through a `.env` file and pass it to `act`, but I couldn't get it
   working.
2. Run this command `act -j codeql -s GITHUB_TOKEN=<MY_PAT>`

Setting the `CODEQL_LOCAL_RUN` env var will fill in missing env vars
that the action needs, but isn't set by `act`. It will also avoid
making api calls to github that would fail locally.

This is a refactoring discussed in
https://github.com/github/dsp-codeql/issues/36

https://github.com/avajs/ava/blob/master/docs/recipes/debugging-with-vscode.md recommends passing the `debug` option to Ava.  However, in my experience Ava waits indefinitely when this option is used, without actually running any tests.

The increased timeout setting is so that tests won't fail prematurely because you're slowly stepping through code.

https://github.com/github/codeql-action/pull/94#discussion_r448502825