Add AnnotationSeries data type

[stephprince]

Fix #97. These changes:

• add the AnnotationSeries class
• add convenience methods for creating an AnnotationSeries dataset and adding annotations to the file
• add testing for the class and convenience methods

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 97.43590% with 3 lines in your changes missing coverage. Please review.

Project coverage is 92.01%. Comparing base (c2ee9e6) to head (a929d87).

Files with missing lines	Patch %	Lines
src/nwb/misc/AnnotationSeries.cpp	92.30%	2 Missing ⚠️
src/io/hdf5/HDF5RecordingData.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #141      +/-   ##
==========================================
+ Coverage   91.83%   92.01%   +0.18%     
==========================================
  Files          58       61       +3     
  Lines        3893     4009     +116     
  Branches      256      262       +6     
==========================================
+ Hits         3575     3689     +114     
- Misses        308      310       +2     
  Partials       10       10              

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[stephprince]

@oruebel this is ready for you to re-review