This commit only adds Home-Manager specific options, we should add
sections for the different kind of modules too.
This is _not_ added to the man docs, as it is more complex. If need
arises we could look into how to do it.
To enable some features (like adding tree-sitter queries) we need to add
files to specific directories in the runtime path (queries/lang/file.scm
for tree-sitter queries for example).
This commit adds support for specifying such files. You must be careful
to not have any collisions between `files` and `extraFiles`.
