Consider moving to a consistent naming scheme for temporary scratch buffers

[echasnovski]

Contributing guidelines

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

Module(s)

mini.animate, mini.clue, mini.colors, mini.completion, mini.deps, mini.extra, mini.files, mini.git, mini.icons, mini.map, mini.notify, mini.pick, mini.starter, mini.test

Description

Currently almost all temporary scratch buffers are unnamed, which sometimes makes :buffers! output confusing.

A popular approach (already done in 'mini.git') is like 'minigit://'.

A big downside is the need to ensure that buffers don't have duplicating names (as it is not allowed by Neovim itself).

[echasnovski]

This should now be implemented on latest main. The most serious changed compared to the previous behavior is the name of the 'mini.starter' buffer: when opening Neovim it was Starter (which showed rather nicely in the statusline and is more or less user-friendly) and now it is ministarter://1/welcome (which looks somewhat intimidating, but that is the price for consistency).

On the upside, the :buffers! is now much more explicit about its permanent hidden buffers. They are mostly there for performance reasons (no need to create-delete-create-delete-etc buffer for the same purpose, just one buffer is reused) and now less confusing than all [Scratch] and [No name] entries that were there previously.