The urls that we generate for mobile post notifications don't take into
account the subfolder url if a site happens to have one configured. When
this happens when you tap on a new mobile notification it takes you to
a url that doesn't work because it is missing the subfolder portion.
I honestly think this should be handled in the Post model like we do
with the Topic model. `Post.url` should know how to handle subfolder
installs, but that seemed like a very risky change because there are
lots of other places in the codebase where we tack on the base_path and
I didn't want to risk duplicating it.
I also found a small typo in the topics controller spec.
Zeitwerk simplifies working with dependencies in dev and makes it easier reloading class chains.
We no longer need to use Rails "require_dependency" anywhere and instead can just use standard
Ruby patterns to require files.
This is a far reaching change and we expect some followups here.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
