This PR adds the first use of Uppy in our codebase, hidden behind a enable_experimental_image_uploader site setting. When the setting is enabled only the user card background uploader will use the new uppy-image-uploader component added in this PR.
I've introduced an UppyUpload mixin that has feature parity with the existing Upload mixin, and improves it slightly to deal with multiple/single file distinctions and validations better. For now, this just supports the XHRUpload plugin for uppy, which keeps our existing POST to /uploads.json.
This PR adds uppy to the project with a custom JS build and the shims needed to import it into our JS code. We need a custom build of Uppy because we do not use webpack for our JS modules/build. The only way to get what you want from Uppy is to use the webpack modules or to include the entire Uppy project including all plugins in a single JS file. This way we can just use the plugins we actually want. Future PRs will actually use Uppy!
The emoji-picker is a specific piece of code as it has very strong performance requirements which are almost not found anywhere else in the app, as a result it was using various hacks to make it work decently even on old browsers.
Following our drop of Internet Explorer, and various new features in Ember and recent browsers we can now take advantage of this to reduce the amount of code needed, this rewrite most importantly does the following:
- use loading="lazy" preventing the full list of emojis to be loaded on opening
- uses InterserctionObserver to find the active section
- limits the use of native event listentes only for hover/click emojis (for performance reason we track click on the whole emoji area and delegate events), everything else is using ember events
- uses popper to position the emoji picker
- no jquery code
