Update developer installation documentation

Make developer installation easier to understand.
Update developer docs.

Include dev installation in TOC.

Fix up some small things.
Merge branch 'enhancement/16221' into develop

* enhancement/16221:
  Update developer docs.
  Update developer installation documentation
wsgi.py: Remove unnecessary additional paths

refs #16269
Move novnc from root folder into static folder

refs #16269
settings/base: Remove novnc from STATICFILES_DIRS

No longer necessary with novnc in our static files folder.

refs #16269
manage.py: Use full package path to settings

refs #16269
Move setup.sh and build_wheels.sh into main gwm repo.

refs #16269
Rework settings.

Settings are use the following precedence:
base.py is the defaults, then /opt/ganeti_webmgr/config.yml is read and it's
settings are used. Finally settings.py is used, if it exists.

Each settings file does not wipe settings from previous files, only
overriding settings it's defined itself.

refs #16269
Fix an error in base.py. Update setup script.

Add pyyaml to requirements

refs #16269
settings/base: Use full python module path to django apps

refs #16269
settings/base: Add more require settings as defaults

refs #16269
Rewrite all imports to import from ganeti_webmgr module.

To make this into a proper python package, and to use django-admin.py this is
necessary. We can now import any of ganeti_webmgr's modules and not worry about
pythonpath.

refs #16269
Use fully qualified imports for custom fields

Had to update migrations in order for the migrations to access custom fields

refs #16269
Use fully qualified module in urls

refs #16269
Update refreshcache to use fully qualified imports.

refs #16269
Update setup.sh to create config dir

Also fix a small typo in setup.sh to fix an error.

Store executable permissions on scripts in git.

refs #16269
Update docs with new installation procedure.

Updates a lot of piotrs documentation to mesh with the changes made, regarding
configuration, and the setup.sh script.

refs #16269
Fix typo on setup script when creating config dir.

refs #16269
Update deployment documentation.

Deployment docs now reflect latest installation procedures.

General cleanup as well.

refs #16269