[c++/python/r] Pushdown SOMA object management to C++

[XanthosXanthopoulos]

Issue and/or context: Push SOMA object lifetime management to C++

Changes:
This PR introduces the following changes:

• SOMACollection caches handles to its member when first accessed. These handles are now used to construct the Python and R wrapper objects to avoid reopening or implementing the caching in the API side.
• Metadata handling is now utilizing a variant to hold the decoded TileDB metadata. This change removes the constraint to hold an open reference a TileDB array/group in order to read the metadata.
• Metadata caching is now part of the common C++ implementation for SOMAGroup and SOMAArray. Both Python and R APIs can now access the metadata in the same way and their metadata caches are now removed.
• The close method now accepts an optional argument to define whether members of a group should be closed once a group is closed.
• Reopening a SOMAObject now does not recreate the C++ handle but rather it reinitialized the same handle (but can and will make member objects invalid)

Notes for Reviewer:
The R devel error is not related to these changes.

[codecov]

Codecov Report

❌ Patch coverage is 69.43574% with 195 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.90%. Comparing base (1ba587f) to head (0abb3c9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4436      +/-   ##
==========================================
- Coverage   85.27%   84.90%   -0.37%     
==========================================
  Files         136      136              
  Lines       21263    21344      +81     
==========================================
- Hits        18132    18123       -9     
- Misses       3131     3221      +90     

Flag	Coverage Δ
python	88.19% <96.55%> (-0.25%)	⬇️
r	83.13% <65.15%> (-0.40%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
python_api	88.19% <96.55%> (-0.25%)	⬇️
libtiledbsoma	∅ <ø> (∅)

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[jp-dark]

The CI should be fixed by a rebase or merge on main.

[jp-dark]

I haven't finished reviewing this yet, but so far it is looking good. I have a couple small comments. As discussed offline, I'd also like to see some unit tests directly on the new metadata class.