feat: New subcommand for plotting bam files

[fxwiegand]

This PR introduces a new subcommand rbt plot-bam that allows the user to generate vega-lite plots (à la rbt vcf-report) from given bam file(s) and a fasta reference. An example usage would be:

rbt plot-bam -b /path/to/my.bam  -b /path/to/my_other.bam --region chr1:3973700-3974000 --reference /path/to/fasta.fa > plot.html

All resulting plots are self contained in a single html file for easy exchange with, for example, fellow researches.

Todos:

• Basic functionality
• Support for multiple bam files

[tedil]

Sorry for hijacking your PR. I initially only wanted to fix a small issue that I encountered, but this snowballed quite a lot. I should have separated this into a different PR, but here we are...

[fxwiegand]

Sorry for hijacking your PR. I initially only wanted to fix a small issue that I encountered, but this snowballed quite a lot. I should have separated this into a different PR, but here we are...

No problem! If the code benefits (almost) everything is fine for me 👍

self-reviews shouldn't be allowed!