cmake: add headers to interface library

[timblechmann]

cmake 3.19 allows headers to be added to interface libraries in order to populate IDE projects

[timblechmann]

compare: https://cmake.org/cmake/help/latest/command/add_library.html#interface-libraries

[codecov-commenter]

Codecov Report

Merging #1057 (2ef4d35) into cpp_master (1edfba0) will not change coverage. The diff coverage is n/a.

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Additional details and impacted files

@@             Coverage Diff             @@
##           cpp_master    #1057   +/-   ##
===========================================
  Coverage       85.60%   85.60%           
===========================================
  Files              79       79           
  Lines            5023     5023           
===========================================
  Hits             4300     4300           
  Misses            723      723