Support yazi flavors

[mikavilpas]

Hi, here's an idea.

Flavors (BETA)
The "flavor" is a pre-made Yazi theme, while what we typically refer to as a "theme" is the user's own theme, i.e. ~/.config/yazi/theme.toml file.

The purpose of separating them is to allow users to customize their preferences more conveniently on top of an existing flavor, without having to modify those flavor files. This makes it easier to update, as there won't be conflicts when pulling from Git.

Behind the scenes, Yazi merges the user's theme.toml with the flavor's flavor.toml automatically, and the user's always takes precedence over the flavor.

https://yazi-rs.github.io/docs/flavors/overview

If you'd welcome a PR about this, please let me know and I can maybe contribute it.

[uncenter]

Duplicate of #1.