This commit changes the emoji uploader to use the UppyUploadMixin,
and makes some minor changes to the emoji uploader (tightening the
copy for drag and drop and adding a percentage for the upload).
Since no other uppy upload mixin components have needed to upload
multiple files so far, this necessitated adding a tracker for the
in progress uploads so we know when to reset the uploader once all
uploads are complete.
At the moment, the emoji uploader cannot be used for direct S3 uploads
because the admin emoji controller creates other records and does other
magic with the emojis. At some point we need to factor this kind of thing
into the ExternalUploadManager.transform! action to complete external
uploads.
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
