Autobuild using CodeQL CLI

[henrymercer]

This PR implements autobuilding using the hidden database autobuild CLI subcommand. This simplifies the implementation of autobuild, opens the door to sharing more code between the CodeQL Action and third party CI for CodeQL, and enable us to more efficiently implement new features like improved diagnostics for autobuilders.

We will gradually roll this out for CodeQL CLI 2.12.6 and later using the code_scanning_cli_autobuild_enabled feature flag. While the CLI and Action implementation of autobuild is very similar, we will not enable this by default on GHES 3.9 to reduce risk.

Merge / deployment checklist

• [x] Confirm this change is backwards compatible with existing workflows.
• [x] Confirm the readme has been updated if necessary.
• [x] Confirm the changelog has been updated if necessary.

[henrymercer]

Moving back to draft as there's some more work here to send telemetry about the set of languages we tried to autobuild and the language that failed, if relevant.

[angelapwen]

Makes sense — let me know when you want me to take a look!

[henrymercer]

Closing this in favour of using build modes and having database trace-command --use-build-mode determine how to extract the code.