Setup Codeql with access token

[mikael-s-persson]

For security reasons, we need to setup codeql with a personal access token secret to be able to pull submodules. I do not have the sufficient access rights to add the access token. Thomas, can you do that?

The build / test commands for this repo should be:

bazel build -c opt --config=libc++ third_party/eigenmath_tf2:all
bazel test -c opt --config=libc++ third_party/eigenmath_tf2:all

The steps to set up the codeql (as per Thomas) are as follows:

Set up a 'classic' personal access token ('fine grained' didn't work for me, lmk if you get that to work).
Add that token as a secret to the repo you're working with (https://github.com/theteamatx//settings/secrets/actions -> 'new secret')
Add a .github/workflows/codeql.yml. Use the secret for the checkout action.
This is my version: https://github.com/theteamatx/x-edr-eigenmath/blob/squash/.github/workflows/codeql.yml
You'll want to use the name you gave the secret in that script.
(Also, do not use the bazel cache action, that breaks the codeql analysis if no actual build happens).