Proof of concept for running command in visual mode

[biozz]

This is a proof of concept to resolve #1.

• It is not so pretty, but it works on multiple lines with :Whop command
• It doesn't work on a range inside one line
• It doesn't work after selecting a command via vim.ui.select and Telescope

And there is also a caveat that currently commands are define with % prefix, which has to be substituted with <,'>, that's why I am thinking about changing the API to make % in the beginning of the text command optional.

Please leave a comment what do you think about this POC, thank you.