Add support for "surround copy (yank)" and "surround paste"

Contributing guidelines

• I have read CONTRIBUTING.md
• I have read CODE_OF_CONDUCT.md

Module(s)

mini.surround

Description

I was playing with my mini.surround config the other day, and I realized that occasionally I want to "copy" a surround, particularly complex ones like "f", and "paste" the same text in another piece of code.

Thinking about it conceptually, executing a command such as "syf" over a function call like vim.print(my_variable), so it would internally store { left = "vim.print(", right = ")" }. Then it should be possible to execute spiw over my_other_variable to get vim.print(my_other_variable).

I it a go in implement this feature, and it was easier to implement than I anticipated. If there's interest, I can format it and open a proper pull request.

Start with the mini.surround module and the implementation shown in the linked comparison branch. Check how the reported syf and spiw examples should behave, then determine the module’s expected completion criteria from that proposal. Done means the surround can be copied from one text region and pasted onto another, including complex surrounds such as f.