eww: string based config

[b3nb5n]

Description

change eww options to allow for configuration via nix. the current implementation sets the entire config directory from a source path which makes it so the entire config must be static files, and the config cannot be split up/appended to from other modules. setting the entire directory also makes it so that fixing this must break backwards compatibility (as far as i can tell). I dont know what the policy is for breaking changes, but im happy to update with any necessary changes

Checklist

• [ ] Change is backwards compatible.

• [x] Code formatted with ./format.

• [x] Code tested through nix-shell --pure tests -A run.all or nix develop --ignore-environment .#all using Flakes.

• [x] Test cases updated/added. See example.

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• If this PR adds a new module

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Maintainer CC

@mainrs