[3006.x] Fix env

[cmcmarrow]

What does this PR do?

fix __env__

Changes:

• Place remotes branch/tag in its own folder ../salt/../hash/branch
  • This includes locks and links
• Clear gitfs cache on salt version change
  • This is so people don't need to manually clear salt cache when upgrading
• Add salt working dir ../salt/../work/hash/branch
  • This is so we decrease the chances of stepping on git
• add fetch_on_fail checkout(self, fetch_on_fail=True)
  • This is so gitpillar does not need worry if a fetch is required when working with dynamic branches
• Fix clean_old_remotes
• Fix fetch for __env__
  • add fetch_request - when Gitbase.fetch_remotes is called the current dynamic branch will fetch and all its sister branches will have a fetch_request file placed in its salt working dir. When sister branch inits or goes to checkout it will see the fetch_request and run fetch
• Tests

^ fixs
salt-call pillar.data pillarenv=foo
salt-run git_pillar.update

TODO later PR:

• remove old remotes branch's/tags
  • Make a timestamp file every time a gitprovier object is made in remote branch
  • clear_old_remotes() will remove any remote branch that has out lived its time to live.
• Move repo locks to salt working dir

What issues does this PR fix or reference?

Fixes: #65002
Fixes: #64999

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

[tysonnorris]

A question on this - is it safe to use multiple gitfs branches/envs on same salt-master BEFORE this change if we set gitfs_global_lock: False?

I assume it is safe AFTER this change, especially if the locks move to salt working dir.