Add string context and location filters to the translate interface

Re-rolled #74 on 10.0.x

Readding the D7 patch that was hidden by @Lekstat

@Lekstat why did you hide your own patch in #79?

This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request → as a guide.

The issue summary could be updated to show what the proposed solution is? Remaing tasks, etc.

Also will need test coverage to ensure it doesn't break.

I had some issues in #74 on the project for which I'm working on. The code section where all the available string translation contexts are fetched in the function translateFilters() didn't apply.

This is an updated version of the patch where the said code segment is placed between the filters array and language fetching sans English.

#83 seems to have some linting errors, please adjust those so that the tests can pass :)

FILE: /var/www/html/core/modules/locale/src/StringContextInterface.php
----------------------------------------------------------------------
FOUND 2 ERRORS AFFECTING 2 LINES
----------------------------------------------------------------------
9 | ERROR | [x] Opening brace should be on the same line as the
| | declaration
16 | ERROR | [x] Expected 1 blank line before function; 0 found

All right, as stated in #84, these should be fixed with the version provided in this comment, #85.

@jheinon_finland Drupal core issues are fixed in development versions. So please don't move versions down.
Current development versions is 10.1.x. Maybe the patch can be applied to previous versions and back-ported if needed but that's up to the core maintainers.

Issue summary still needs updating.

Tests are still needed.

And yes interdiffs need to be uploaded for #83 and #85

In this, I will upload the interdiff between versions #83 and #85. To answer #86, it appears it's not possible to edit an old comment and provide a file with it, so I will be uploading the interdiff file in this comment.

per #87

parisek → closed merge request !4173

parisek → closed merge request !4175

Updated MR to support Drupal 10, unfortunately couldn't rebase

Rebased MR 4174.

Is there any patch for 10.2.1 ?
Thanks