lint: Add lint rule to warn people making changes to static/locale.

[rishig]

We occasionally get PRs with translations or other fixes to the files in static/locale, due to a reasonable misunderstanding of how our translation system works. It would be great to add some sort of warning that points people either to transifex or to our translation documentation.

[zulipbot]

Hello @zulip/server-i18n, @zulip/server-testing members, this issue was labeled with the area: i18n, area: testing-infrastructure labels, so you may want to check it out!

[timabbott]

I wish .gitattributes supported controlling git grep, but it doesn't (just checked), since that's what we really want here. We could try adding a static/locale/README.md. I think the next most natural thing after that would be to have a zulipbot feature to complain about diffs touching that directory.

@synicalsyntax would that be hard to do?

[synicalsyntax]

@timabbott Personally I think it might be better to have file diffs checked in a testing suite, but it should be possible with zulipbot; can you open an issue?

[timabbott]

The thing which is tricky here is that we don't really have test suites that look at the Git history (as opposed to the current state of the repo). I guess we could look at using gitlint for this if it supports inspecting the commit file list? @tommyip do you know if that's possible?

[tommyip]

@timabbott gitlint only checks the commit messages by default. There is a command to inspect the commit file list, git diff-tree --no-commit-id --name-only -r upstream/master..HEAD^, we could add this as a custom gitlint rule or just put it somewhere in tools/lint.

[zulipbot]

Hello @zulip/server-i18n, @zulip/server-testing, @zulip/server-tooling members, this issue was labeled with the "area: i18n", "area: testing-infrastructure", "area: tooling" labels, so you may want to check it out!