This allows a configuration to be set as a function that will be passed
autoloadArgs. This is useful when each configuration is in its own file
when autoloading.
The fact it uses bash is an implementation detail. Update the
documentation to state that the input is a file name glob rather than a
bash case match. Updates the default formatters to not rely on being a
bash case statement.
This allows for conveniently making flakes callable.
Setting this is expected to be uncommon in general, but having the
option is useful as flakelight module flakes can use this to reduce the
boilerplate in using them.
