Cleanup of declaration of taclet options

[WolframPfeifer]

This PR does some cleanup in the .key LDT files:

• The declaration of taclet options is moved from ruleSetsDeclarations.key into a separate file optionsDeclarations.key.
• sort and function declarations are moved from ruleSetsDeclarations.key and javaRules.key into the new file javaHeader.key.
• The loading order is changed slightly: First load the taclet options, then the rule sets, and then all the theories.
• Provide a better error message when a sort declaration is ignored due to an earlier declaration.
• A old dangling comment of a legacy taclet option which does not exist anymore (optimisedSelectRules) was removed.

Type of pull request

• [x] 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)
• [x] There are changes to the (Java) code
• [x] There are changes to the taclet rule base (functionality should not change though)
• [ ] 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.
• [ ] I have tested the feature as follows: ...
• [ ] I have checked that runtime performance has not deteriorated.

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 37.85%. Comparing base (fb58c33) to head (0885db4).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3408 +/- ## ============================================ - Coverage 37.85% 37.85% -0.01% Complexity 17042 17042 ============================================ Files 2082 2082 Lines 127290 127292 +2 Branches 21441 21441 ============================================ - Hits 48184 48182 -2 - Misses 73194 73198 +4 Partials 5912 5912 ```

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[WolframPfeifer]

@mattulbrich This is the PR I mentioned yesterday. It just refactors the declarations in some .key files a bit and should not introduce any functional changes (apart from a more helpful message when a symbol is declared twice). It would be nice if you could take a quick look ... Thanks in advance!