externalise jquery using jquery-rails-cdn and jquery-rails fallback

[Tlazypanda]

Fixes #7920

Externalise jquery using jquery-rails-cdn and jquery-rails fallback to improve performance in terms of -
Automatically fallback to jquery-rails' bundled jQuery when:

On top of that, if you're using asset pipeline, you may have noticed that the major chunks of the code in combined application.js is jQuery. Implications of externalizing jQuery from application.js are:

• Updating your JS code won't evict the entire cache in browsers.
• Cached jQuery in the client browsers will survive deployments.
• rake assets:precompile will run faster and use less memory.

• PR is descriptively titled 📑 and links the original issue above 🔗
• tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with rake test
• code is in uniquely-named feature branch and has no merge conflicts 📁
• screenshots/GIFs are attached 📎 in case of UI updation
• ask @publiclab/reviewers for help, in a comment below

Thanks!

[gitpod-io]

[codecov]

Codecov Report

Merging #8161 into main will decrease coverage by 2.22%.
The diff coverage is 64.65%.

@@            Coverage Diff             @@
##             main    #8161      +/-   ##
==========================================
- Coverage   82.10%   79.88%   -2.23%     
==========================================
  Files         100      100              
  Lines        5751     5866     +115     
==========================================
- Hits         4722     4686      -36     
- Misses       1029     1180     +151     

Impacted Files	Coverage Δ
app/controllers/wiki_controller.rb	81.92% <ø> (-3.08%)	⬇️
app/controllers/spam2_controller.rb	75.59% <56.38%> (-24.41%)	⬇️
app/controllers/admin_controller.rb	78.60% <100.00%> (-1.40%)	⬇️
app/controllers/subscription_controller.rb	59.59% <100.00%> (-10.82%)	⬇️
app/models/comment.rb	77.51% <100.00%> (+0.62%)	⬆️
app/models/node.rb	90.82% <100.00%> (-0.24%)	⬇️
app/models/tag.rb	97.50% <100.00%> (ø)
app/channels/application_cable/channel.rb	0.00% <0.00%> (-100.00%)	⬇️
app/channels/application_cable/connection.rb	0.00% <0.00%> (-100.00%)	⬇️
app/channels/user_channel.rb	0.00% <0.00%> (-83.34%)	⬇️
... and 14 more

[Tlazypanda]

@jywarren @cesswairimu can you kindly review? Thanks ✌️ Should I first push on unstable? 😅

[gitpod-io]

[gitpod-io]

[gitpod-io]

[stale]

Hi 😄, this issue has been automatically marked as stale because it has not had recent activity. Don't worry you can continue to work on this and ask @publiclab/reviewers to add "work in progress" label 🎉 . Otherwise, it will be closed if no further activity occurs in 5 days -- but you can always re-open it if you like! 💯 Thank you for your contributions 🙌 🎈.