Because the code was so complex before, we had to create an object and
then cast that object into a `StoreId` rather than just creating a
`StoreId` object right away.
With this patch, we're using the code-generation approach to generate a
function that creates a `StoreId` object based on the name of the
current module. That's way easier and error handling was also improved
by the switch to the new implementation.
The patch also includes a rewrite of all usages of ModuleEntryPath and
changes them to `module_path::new_id()` calls.
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
