The blog archive page tables have `table-borderless`, but
bootstrap-table JS adds `table-bordered` by default and this forces an
`!important` border.
Since these tables are also supposed to be borderless, this PR excludes
them from bootstrap-table, just like the news and CV table are.
summary:
- adds prettier formatter configuration
- formats the entire repo using prettier, ignoring minified files
(`*.min.css`) and heavy generated html
- changes extensions of all `.html` files to `.liquid`, which is more
correct and necessary for prettier to work correctly
- replaces "%-" and "-%" with just "%" — manual liquid formatting using
minus signs is superfluous since we are compressing and minifying the
code anyway
- adds CI action for running prettier check on PR and pushes to master