Merge all currently "fixed in dev" issues into main

[PaulHancock]

This includes the following issues:

• Associate PSR with a candidate using a button #33
• Add ability to classify many candidates from the ratings page #42
• Create a method for users to store metadata with the candidate objects #44
• Update the RA/DEC search on the candidates table page to be a cone search #45
• Candidate rating page to include link to the candidates table #46
• Issues on Candidate Ratings Table page #54
  • Cone search RA/DEC can now be provided in either decimal degrees or in hms/dms format.
• Issues on Candidate Rating page #55
  • When there are no unrated candidates for a project, the text "Choose a different project in the sessions settings page" is now a link to the sessions settings page.
  • The mouse cursor changes on hover for the two images (zoom in/out) and for the note text
  • All links to external pages now open in a new tab
  • Links that open in new tabs have a icon to indicate this
  • A classification is required to submit a rating. The form is now validated on the client and will not allow submission unless the user has selected an option.
• Issues on Database download page #56
  • All download links are now fixed and working as intended
• Update page header to include link to admin page #57
  • Logged in admin users will see this link

As of 08/10/2024 the Nimbus instance is serving the dev branch of this project. Accepting/merging this PR will mean that we can revert back to serving the main branch.

This PR also updates all the documentation to bring it in line with the current version of the web-app. When the PR is merged the documentation on readthedocs.io will be automatically regenerated.