Bug 41842, 41845 and more: move about:tor outside torbutton, remove old preferences and old logic

Merge Info

Related Issues

• #41482 #41842 (closed)
• #41845 (closed)

Backporting

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

(Optional) Justification

• Emergency security update: patchset fixes CVEs, 0-days, etc
• Censorship event: patchset enables censorship circumvention
• Critical bug-fix: patchset fixes a bug in core-functionality
• Consistency: patchset which would make development easier if it were in both the alpha and release branches; developer tools, build system changes, etc
• Sponsor required: patchset required for sponsor
• Other: please explain

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
  • NOTE: if your changeset includes patches to both base-browser and tor-browser please clearly label in the change description which commits should be cherry-picked to base-browser after merging

Issue Tracking

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

Review

Request Reviewer

• Request review from an applications developer depending on modified system:
  • NOTE: if the MR modifies multiple areas, please /cc all the relevant reviewers (since gitlab only allows 1 reviewer)
  • accessibility : henry
  • android : dan
  • build system : boklm
  • extensions : ma1
  • firefox internals (XUL/JS/XPCOM) : ma1
  • fonts : pierov
  • frontend (implementation) : henry
  • frontend (review) : donuts, richard
  • localization : henry, pierov
  • nightly builds : boklm
  • rebases/release-prep : dan_b, ma1, pierov, richard
  • security : ma1
  • signing : boklm, richard
  • updater : pierov
  • misc/other : pierov, richard

Change Description

The aim of this MR is creating a new commit for about:tor, primarily.

I decided to move also TorCheckService with it, because about:tor it's the only consumer.

We might do something better for it in the future, maybe.

Removing about:tor also allowed to remove some preferences, and at this point I've decided to group together also all the preferences migration for the migration functionality (I thought it didn't make sense to make several bumps for the same alpha).

Also, at the beginning of the branch I've decided to move to ES modules a few of our classes beacuse it's something we need to do, and these files were modified in a lot of commits.

So, to simplify everyone's life, I decided to do it as a first thing.

If you really don't like it, I can create a couple of additional MRs in addition to the about:tor changes.

/cc @richard @henry @ma1