[ENHANCEMENT] Allow updating + creation of categories linked to each post

[SethCram]

Is your feature request related to a problem? Please describe.

• Yes, posts don't currently have their category fields implemented

Describe the solution you'd like

• Add a list of common post categories to Categories model
• Add a drop down menu to link different categories to a post at creation time
• Allow the categories a post is linked to to be updated

Additional context

• common post categories may need to be added to Categories model manually

Development

• Add a list of common post categories to Categories model
  • did so thru postman
  • need a better way
• Add a drop down menu to link different categories to a post at creation time
  • had to create a dropdown w/ multi-selectable items
    • since want to link at most 3 categories to each post
    • downloaded new lib for purpose
    • when items selected, added horizontally to dropbox and expands it
      • ideally, dropbox would grow vertically
  • retrieved categories from using api + displayed them in multiselect
  • stored selected vals in a reference
    • used that ref to assigned categories to post at publish time
    • can only access component based functs via ref
  • added some padding so not right nxt to other comps
• Allow the categories a post is linked to to be updated
  • had to update through dropdown so reused categories call funct
    • could possibly put all of these reused functs into a file somewhere to call??
  • prefilled dropdown with post's current categories
  • had to use a local categories state var for responsiveness
    • possibly bc post wasnt being re-retrieved after update
    • and i dont think it ever is unless reload or navigation to diff page\