DE-743 | MDI/ZKD Indexes

[aMahanna]

Internal discussions have established that an mdi index is an alias for a zkd index, similar to the hash index & persistent index situation.

Given that python-arango never had support for zkd index creation, this PR introduces both add_zkd_index and add_mdi_index

i.e

• MDI (>=3.12)
• ZKD (<3.12)

Ref: https://docs.arangodb.com/3.12/index-and-search/indexing/working-with-indexes/multi-dimensional-indexes/

Happy to address this in another way, perhaps there's no need for 2 methods?

[codecov-commenter]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (99f5d9b) 98.45% compared to head (b93971a) 98.26%.

Files	Patch %	Lines
arango/collection.py	55.55%	8 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #316      +/-   ##
==========================================
- Coverage   98.45%   98.26%   -0.19%     
==========================================
  Files          26       26              
  Lines        4136     4154      +18     
==========================================
+ Hits         4072     4082      +10     
- Misses         64       72       +8     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[apetenchea]

LGTM

[aMahanna]

After internal discussions, this PR will be merged, but the following changes will be made to index creation:

• Make _add_index public
• Set a deprecation warning to all individual add_*_index methods
• Update indexes.rst to use the generalized add_index method
• Remove ZKD/MDI add index method, keep existing tests (reworked for add_index)