Update System Themes source path

[Kasui92]

Looking at this PR and @dougburks’ work, I’m wondering if system themes could be made independent from $HOME/.local/share/omakub/themes .

My themes also live in separate directories. I saw that the latest OhMyDebn release adds symlinks, but wouldn’t it be better to allow configuring the themes path via CLI or settings?

[bjarneo]

So, Aether in itself is made for Omarchy, that is what Aether is. However, as it wasn't that much to make it more standalone, I made the app so it works for other distros.

What I am open for is as mentioned in this comment: #87 (comment)

Or a path, e.g. /.config/themes