This commit adds support for byte compiling lua configuration files.
It's enabled by default (if byte compiling is enabled at all) and can be
disabled with `performance.byteCompileLua.configs` toggle.
To implement this feature `extraFiles.<name>.finalSource` internal
read-only option is introduced. `source` option cannot be used because
it's user configurable. In order to access the values of the
`performance.byteCompileLua` options, parent config is added to
specialArgs of extraFiles submodule. Then the usages of `source` option
changed to `finalSource` in all relevant places (filesPlugin and
wrappers).
Added more helpers for various cases of byte compiling:
* `byteCompileLuaFile` byte compiles lua file
* `byteCompileLuaHook` is a setup hook that byte compiles all lua files
* `byteCompileLuaDrv` overrides derivation by adding byteCompileLuaHook
to it
Added tests to validate that extraFiles specified by various methods are
handled correctly. Added a separate home-manager test, that is intended
to validate that extraFiles propagated to wrapper modules are correctly
byte compiled.
Moved `extraFiles` from `modules/output.nix` into its own file `modules/files.nix`.
Users should now assign text to a `text` attribute, however they could
also assign a file path to a `source` attribute instead.
The old method of directly assigning a string still works, and is
coerced to the new type along with a deprecation warning.
