Use config api for server settings WD-7389 instance defaults WD-7390 and project defaults

[edlerd]

Done

• rely on the config api for:
  • server settings (used to be hard coded in a json file)
  • instance form defaults and help texts (used to be hard coded in a js object)
  • profile form defaults and help texts (used to be hard coded in a js object)
  • project form defaults and help texts (used to be hard coded in a js object)

Fixes WD-7389 WD-7390

QA

1. Run the LXD-UI:
   • On the demo server via the link posted by @webteam-app below. This is only available for PRs created by collaborators of the repo. Ask @lorumic or @edlerd for access.
   • With a local copy of this branch, run as described here.
2. Perform the following QA steps:
   • check settings page
     • edit settings
     • reset settings
   • check create instance form: all default values (From: LXD) and help texts (the gray explanation)
     • create instance > advanced > all sections and all possible overrides
   • check create profile form: all default values (From: LXD) and help texts (the gray explanation)
     • profiles > create profile > advanced > all sections and all possible overrides
   • check edit project form: all default values (From: LXD) and help texts (the gray explanation)
     • configuration > edit > all sections and all possible overrides

[webteam-app]

Demo starting at https://lxd-ui-543.demos.haus

[mas-who]

Just some minor comments, I'd feel more comfortable if someone else also have a review since I may not be the most familiar with the code yet

[mas-who]

Checked during QA:

• Created a project test-config-api-project and checked every setting for edit saves and reset to default value.
• Checked create instance form, create profile form and edit project form for available settings as well as overrides. All settings and override options seem to display correct explanations.
• Checked all links within setting explanations that they navigate to the correct documentation.

[lorumic]

Mostly a bunch of assignment shorthand suggestions (I recommend using the "Add suggestion to batch" button if you want to implement them, because they are a lot), and a few other questions/proposals for tiny improvements. Feel free to merge with or without these changes.