[r] Run clang-format on apis/r/src (except autogen code)

[johnkerl]

While working on #2407 / [sc-51048] and #2406.

This was fully automated via

 clang-format -i  apis/r/src/[a-z]*.cpp

with the exception of a couple fix-ups on //'-style comments.

Note that we enitrely avoid apis/r/src/RcppExports.cpp which is auto-generated.

On this PR I just manually ran the formatter on the relevant source files. On a follow-up PR I'll stop excluding these files from the format-checker which we run on the rest of our libtiledbsoma and pybind11 C++ source:
https://github.com/single-cell-data/TileDB-SOMA/blob/1.14.1/.github/workflows/python-ci-single.yml#L62-L64

Also note that we should move the clang-format checker from python-ci-single.yml to another C++-specific YAML file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.71%. Comparing base (fd1537f) to head (0fd2de9).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3048   +/-   ##
=======================================
  Coverage   89.71%   89.71%           
=======================================
  Files          41       41           
  Lines        4113     4113           
=======================================
  Hits         3690     3690           
  Misses        423      423           

Flag	Coverage Δ
python	89.71% <ø> (ø)

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

Components	Coverage Δ
python_api	89.71% <ø> (ø)
libtiledbsoma	∅ <ø> (∅)