treewide: restructure neovim-flake tree

[NotAShelf]

Take three of #197 and #225.

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DONE

1. Reduces dependency cycles and layered imports in modules/

   • All plugins have been moved to modules/plugins/
   • Option definitions separated from configurations
   • Basic and Core have been isolated as modules/core and modules/neovim (previously basic)`
     • core will contain wrapper and build related files
     • neovim will contain the most basic vim/neovim options that are passed to base configurations.

2. Cleans up and re-organizes lib so that files and functions are easier to search by name.

3. Moves vim-dirtytalk to plugins.

TODO/TBD

Things I want to do:

• Move neovim config builder/helper functions into lib, and call from lib where necessary. This has been an issue while implementing the home manager module, and I'd like to avoid repeating the same mistake again.

Things I might want to do:

• Get rid of inputs per-plugin. It's a nice idea, but flakes suck. Hundreds of inputs that a user will likely not even think about overriding in their whole usage of this flake is, I assume, burdening. If my fellow co-maintainers @FrothyMarrow and @horriblename agree; I'd like to fall back to either customizable package options, or a packages list that gets passed to Neovim wrapper.
• Other suggestions by contributors and maintainers alike

[NotAShelf]

I officially consider this ready to go, it's not perfect but I will revise the structure as the need arises. I wanted to revise lib a bit, but I think that's going to be to big of an endeavor right now - one that I do not have the energy for. Unless @horriblename or @FrothyMarrow have a request or any requests for changes, this can be merged.

[horriblename]

the type should already say what's available, I think we can delete this part