implements add_column_transform_regexp feature

[kosack]

This allows one to add column transforms by patterns that match the table name and column name, using re.fullmatch. It adds a new function add_column_transform_regexp(), so the original API does not change.

It also adds an internal helper function _realize_regexp_transforms() that converts transform patterns into explicit transform dicts that are applied as before. This way there is no speed impact compared to the original implementation, as this function is only called during schema generation.

This feature is needed in order to make the DL2 output of #1673 work if we split tables by tel_id, since it allows one to add column transforms to all tables for each algorithm without a huge and complex loop over all possible names.

Technical note: we could replace add_column_transform() with this implementation, i.e. to always treat all transforms as regexps and hide this as an implementation detail, but I decided on simply adding a separate API function for adding by regexp, since otherwise it could make schema generation slow in cases where there are a lot of tables (like DL1 files, etc).

[codecov]

Codecov Report

Merging #1690 (86e088a) into master (8836a96) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1690      +/-   ##
==========================================
+ Coverage   90.52%   90.57%   +0.04%     
==========================================
  Files         186      186              
  Lines       13998    14065      +67     
==========================================
+ Hits        12672    12739      +67     
  Misses       1326     1326              

Impacted Files	Coverage Δ
ctapipe/io/hdf5tableio.py	96.92% <100.00%> (+0.01%)	⬆️
ctapipe/io/tableio.py	93.33% <100.00%> (+0.96%)	⬆️
ctapipe/io/tests/test_hdf5.py	98.47% <100.00%> (+0.06%)	⬆️
ctapipe/io/tests/test_astropy_helpers.py	100.00% <0.00%> (ø)

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[maxnoe]

LGTM