feat: work as a drop-in ls replacement

Currently, exa doesn't support the -t flag in the same way as ls, so it won't work as a drop in replacement. That is, ls -ltra works, but exa -ltra won't work.

An issue existed at the exa repository for this: https://github.com/ogham/exa/issues/519

I also wrote a patch fixing this: https://github.com/ogham/exa/commit/fa76a335fd40d1f81b656b3d602309e7d39bed2f

I tried cherry-picking this, but some conflicts seem non-trivial. I'd appreciate hearing some feedback on the patch first, and if it looks good, I'll like to incorporate it into eza. Notably:

• When -t is specified with arguments, it behaves much like exa -t X.
• When -t is specified without arguments, it behaves like ls.