Add loading indicator when fetching branches and prebuilds

[gtsiolis]

Problem to solve

Loading Branches and Prebuilds for a project can still take a while for active projects, see #5038.

Proposal

Until there's a better way to resolve these perfomance issues, we could introduce a loading indicator when fetching branches and prebuilds to improve the user experience.

This could use the loading indicator being introduced in #5236, see relevant diff. ⚫

Branches	Prebuilds

[atduarte]

It would be also good to do something similar in the prebuild page, as it starts with an "unknown prebuild" title

[gtsiolis]

@jankeromnes since you added the loading indicator on the Branches page in #5809, do you think it makes sense to do the same for the Prebuilds page as it could be slightly slow to fetch prebuilds for active projects. For example, see https://gitpod.io/t/gitpod/gitpod/prebuilds. ❓ Cc @AlexTugarev

[gtsiolis]

Looping in @jldec for visibility.

[jankeromnes]

Yes 👍 happy to add these.

[JanKoehnlein]

/schedule

[roboquat]

@JanKoehnlein: Issue scheduled in the meta team (WIP: 0)

In response to this:

/schedule

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[jankeromnes]

/schedule

Woohoo! Rock'n'roll 😎

[jankeromnes]

/assign

[jankeromnes]

PR: #6984

TODO:

• Loading indicator for Branches
• Loading indicator for Prebuilds
• Stretch goal: Loading indicator / skeleton loader for Prebuild
• Stretch goal: Loading indicator / skeleton loader for Projects

EDIT: (Edited based on #5351 (comment) 🙏)

[gtsiolis]

Loading indicator for Projects

This was also briefly mentioned in a past meta team meeting in regards to #6118 and #6121.

A loading indicator could be a good MVC and a skeleton loader could be even better in a future iteration for the Projects and Prebuild pages due to page structure.