`AnsiHtmlFormatter` and ANSI-aware shell-like lexers

[kdeldycke]

After a year of usage in my Click Extra project and lots of pain trying to integrate it with Click, Sphinx and Furo, I finally reached a point where my stack of monkey-patch work as intended and validates my efforts.

So now I'm wondering if there are some stuff worth contributing back to pygments-ansi-color. Namely:

• AnsiHtmlFormatter: which automatically patch the user-provided style with custom style so you do not have to perform the color_tokens dance.

• A collection of shell-like lexers capable of rendering ANSI codes in Generic.Output.