Switches for typable commands

[the-mikedavis]

Some typable commands might benefit from taking switches to control small parts of their behavior. A few examples of commands that could take advantage of switches:

• :write and friends could take a --no-format switch which prevents auto-formatting (#4853, #4909 (comment))
• :sort and :rsort could be merged into one command with reverse-sorting accomplished by :sort --reverse (#1288 (comment))
• :clear-registers (#5695) could take an --all switch to clear all registers (#5695 (comment))

Kakoune has switches and it has a nice way of showing the available switches in the documentation popup:

A few items worth some discussion:

• Call these "switches" or "flags"?
• Support shorthand switches? For example -a would be a shorthand for --all in the :clear-registers example.

[goyalyashpal]

:config-reload and :config-open can also merged?