Bug 42722: Address clang-format and localization linter issues

Merge Info

Related Issues

• #42722 (closed)
• mullvad-browser#xxxxx
• tor-browser-build#xxxxx

Backporting

I guess this requires a backport if we want to run the linter jobs successfully on 13.x branches.

Timeline

• Immediate: patchset needed as soon as possible
• Next Minor Stable Release: patchset that needs to be verified in nightly before backport
• Eventually: patchset that needs to be verified in alpha before backport
• No Backport (preferred): patchset for the next major stable

Merging

• Merge to tor-browser - !fixups to tor-browser-specific commits, new features, security backports
• Merge to base-browser - !fixups to base-browser-specific commits, new features to be shared with mullvad-browser, and security backports

Issue Tracking

• [?] Link resolved issues with appropriate Release Prep issue for changelog generation

Change Description

The clang-format and localization lint jobs were failing due to missing dependencies in the environment. localization requires Mercurial and clang-format requires most build dependencies, because it runs configure under the hood. To address the issue I created a custom Docker image to use in our CI. This is something we would probably have to do in the near future anyways so it's fine.

I have manually published the image to my fork registry, for now. Ideally I'd like to publish the image from CI and re-build it every time the Dockerfile changes, but I'd rather do that at another time in a follow-up. Nevertheless, I'd prefer the image is published to the main repository for tor-browser and not my fork. I do not have permissions to do so. If we agree this is ok then maybe @pierov can help out with the publishing 😄

Also I've addressed the issue with the pip cache.

How Tested

This MR includes a commit where a cpp and l10n files are changed. This will trigger the jobs that were giving us trouble, to validate that the change works. We are not interested in the actual linting of the files, but just on whether or not we were able to run the linter or not -- which is what was originally failing.

Related to #42722 (closed)