This commit adds the packs and queries from the actions input to the
config file used by the CodeQL CLI.
When the `+` is used, the actions input value is combined with the
config value and when it is not used, the input value overrides the
config value.
This commit also adds a bunch of integration tests for this feature.
In order to avoid adding too many new jobs, all of the tests are
run sequentially in a single job (matrixed across relevant operating
systems and OSes).
Previously, we were being too strict about checking that a pack's
language was being scanned. It was a failure if a pack language
was specified for a language not being scanned.
This input allows users to specify which packs to run. It works in
unison with the packs block of the config file and it is similar to
how `queries` works. They both use `+` in the same way.
Note that the `#TODO` in the pr check is still around, but the CLI
is available. I will remove the TODO in the next commit.
