Flake: diversify wrapper and package

[Rexcrazy804]

• seperated default.nix into two derrivations
• default.nix hosting the wrapper and unwrapped.nix with original qs drv
• passing non list argument to .withModules now displays an appropriate error message (separate pr?)
• reflected these changes onto CI and devShell nix code to override the unwrapped drv accordingly

Motivation

with the former implementation we were unable to call .overrideAttrs to
override the attributes of the underlying UNWRAPPED derivation (say
adding a postPatch)

With the current implementation, we may simply do so by calling
.override { quickshell-unwrapped = <qs-unwrapped with .overrideAttrs>; }

Tests Done

• wrapper builds without errors
• changing wrapper with .withModules does not rebuild everything
• underlying unwrapped derivation's attrs are overridable
• passing non list values to throws an appropriate error message

[Rexcrazy804]

time to fix CI nix code :woe:

[Rexcrazy804]

@outfoxxed could you take a look at this and lemme know what you want changed

[Rexcrazy804]

build failure due to nix being down

[Rexcrazy804]

rebased, no more changes to ci code