CLI: `manim cfg` upgrades!

[Phosphorescentt]

Problem

Similar to #2695. manim cfg write and manim cfg export have very similar functionality but are under different commands. Both commands are also lacking documentation and it's not clear how they differ (if at all). Furthermore, writing config files is very clunky at the moment as all of these commands force the user to go through the configuration file writer which has >50 fields.

Description of proposed feature

I propose a few changes to clean this up:

• manim cfg new that creates a new config file via the CLI wizard that currently exist and optionally produces a default config via a --default flag or similar (the opposite way is also possible and I'm not really sure which is more ergonomic).
• manim cfg install [arg] which takes a config file as an argument and puts it in $HOME/.config/manim/manim.cfg like manim cfg write -l user
• manim cfg edit that edits the config placed in $HOME/.config/manim/manim.cfg using $EDITOR$ with an optional -l flag (similar to manim cfg write) that specifies whether to edit the user config or the cwd config (the second half of this idea is questionable, but I thought it was worth mentioning nontheless)
• manim cfg export which takes the config installed at $HOME/.config/manim/manim.cfg and copies it to the current working directory (maybe not a good name, but the idea still stands)

These are only first ideas so please feel free to rip them apart/suggest improvements :)