Ease the way to use base interpolation schemes for particle interpolators

[Theo-Geo]

I added an overload to aspect::Particle::Interpolator::create_particle_interpolator, which takes an interpolation scheme as a string input. This way one can use the base model functionality that many material models use also for particle interpolators.

Furthermore i added the function get_valid_interpolator_names similar to get_valid_model_names for Material models. It replaces the already existing function "interpolator_object_names", which was declared but did not have any function definition in the interface.cc file. There was no occurrence in aspect where it was used.

For this i also slightly changed the documentation of the existing create particle interpolator, which said that it would take a model name as input though it actually read the interpolator name from a prm.

This functionality will be used in a new interpolator for rotations, where only a set of properties will be averaged with a special algorithm and the rest of the properties should be averaged with a fallback interpolator of the users choice.

Before your first pull request:

• I have read the guidelines in our CONTRIBUTING.md document.

For all pull requests:

• I have followed the instructions for indenting my code.
• I followed the AI Policy:
  • Significant parts of this PR were written by AI (please add a sentence below).
  • AI has not been used in significant ways.

Only honest copy and paste from the material model interface has been used for this PR.

For new features/models or changes of existing features:

• I have tested my new feature locally to ensure it is correct.
• I have created a testcase for the new feature/benchmark in the tests/ directory.
• I have added a changelog entry in the doc/modules/changes directory that will inform other users of my change.