🚧 Update provider js assets

[josemigallas]

Disclaimer: this PR is not about updating every usage of jQuery but to prepare the ground for removing jQuery 1 altogether. We need to identify where it's used, why and what for in order to eliminate every possibility of a breaking chang.

This is part of THREESCALE-9982: Unify jquery across 3scale.

layout/provider.js imports a lot of old scripts and libraries that (some) depend on jquery:

//= require vendor/jquery
//= require highlight/highlight.pack.js
//= require remote
//= require switch
//= require ajax_events
//= require extra_fields
//= require vendor/underscore.min.js
//= require provider
//= require vendor/jquery.iframe-post-form.js
//= require vendor/colorbox/jquery.colorbox.js
//= require threescale
//= require vendor/pluralize
//= require master_application
//= require flash

By moving them into webpack we gain typings and have more control over its use of jquery, therefore making it easier to upgrade.

Verification instructions

⚠️ Hard to say! But here is some info about what each script do:

• ajax_events: adds/removes a spinner to the screen when ajax is used (asynchronous requests via JS). These events are triggered by window.$ (that is, jquery v1) so it's necessary to set event handlers to jquery 1. Ajax is used by jquery-rails, rails_ujs and other similar libraries that are managed by bundler. These libraries are all plugged into window.$.
• remote: this one is very important. The script sets up all remote forms and links (with class .remote) that are to send an ajax request to rails and receive a JS response, instead of loading the whole page again. This should be easy to test, look for forms and links with class remote (or prop remote: true) and verify that using then do not reload the page.
• More to do...

[jlledom]

Pretty hard to review this, I don't know what should I try. Apparently there's a legit cucumber failure. I'll approve if it's fixed.

[josemigallas]

Pretty hard to review this, I don't know what should I try. Apparently there's a legit cucumber failure. I'll approve if it's fixed.

I will split this up in smaller PRs if they make sense.

[mayorova]

Maybe convert this PR into draft, because it seems that it is being split in multiple PRs (which is a good idea) ?