Always sort extension actions in context submenus (+bugfix to allow disabling extensions)

Intended Change

This changes the display of extension-provided context menu actions. If they set a menu path, it will now be respected when constructing the popup menu.

The second commit fixes a bug where it was no longer possible to disable extensions (they would always re-enable on next KeY launch).

Type of pull request

[x] Bug fix (non-breaking change which fixes an issue)
[ ] Refactoring (behaviour should not change or only minimally change)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] There are changes to the (Java) code
[ ] There are changes to the taclet rule base
[ ] There are changes to the deployment/CI infrastructure (gradle, github, ...)
[ ] Other:

Ensuring quality

[ ] I made sure that introduced/changed code is well documented (javadoc and inline comments).
[ ] I made sure that new/changed end-user features are well documented (https://github.com/KeYProject/key-docs).
[ ] I added new test case(s) for new functionality.
[x] I have tested the feature as follows: it works as expected for a new context menu action I added in another PR
[x] I have checked that runtime performance has not deteriorated.

Additional information and contact(s)

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (5b08998) 37.93% compared to head (d893760) 37.93%.

Files	Patch %	Lines
...ka/ilkd/key/settings/ProofIndependentSettings.java	0.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3392 +/- ## ============================================ - Coverage 37.93% 37.93% -0.01% Complexity 17035 17035 ============================================ Files 2060 2060 Lines 126284 126286 +2 Branches 21303 21304 +1 ============================================ Hits 47912 47912 - Misses 72487 72488 +1 - Partials 5885 5886 +1 ```

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KeYProject / key