[WIP] append to sequence file output

[eseiler]

Example usage:

seqan3::sequence_file_output fout{"/tmp/test.sam",
                                  seqan3::fields<seqan3::field::id, seqan3::field::seq, seqan3::field::qual>{},
                                  std::ios_base::app};

• It's annoying, but acceptable, that the fields have to be given.

Old

Example usage:

seqan3::sequence_file_output fout{"/tmp/test.sam",
                                  seqan3::fields<seqan3::field::id, seqan3::field::seq, seqan3::field::qual>{},
                                  {.append = true}};

• It's annoying, but acceptable, that the fields have to be given.
• I just reused sequence_file_output_options for this because I didn't want to add another enum/strong type. We could also do an enum or a bool. Or even a std::ios_base::openmode (with constraints?).
• sequence_file_output_options::append is the only option that's fixed on construction

seqan3::sequence_file_output fout{"/tmp/test.sam",
                                  seqan3::fields<seqan3::field::id, seqan3::field::seq, seqan3::field::qual>{},
                                  {.append = true}};
fout.options.append = false; // No effect

seqan3::sequence_file_output fout{"/tmp/test.sam",
                                  seqan3::fields<seqan3::field::id, seqan3::field::seq, seqan3::field::qual>{}};
fout.options.append = true; // No effect

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.11%. Comparing base (ca62168) to head (599f0f5).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3365   +/-   ##
=======================================
  Coverage   98.11%   98.11%           
=======================================
  Files         270      270           
  Lines       11913    11913           
  Branches      103      103           
=======================================
  Hits        11689    11689           
  Misses        224      224           

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Documentation preview available at https://docs.seqan.de/preview/seqan/seqan3/3365