Add fields for posts (including tags) + openapi docs (2nd time around).

[mattrltrent]

Fields added to Post type

• reply_context (optional): Specifies if the post is "replying" to another post. Think of it as a Quoted Tweet (if you know Twitter).
• school_id: The unique ID (ex: UVIC) of the school the post is associated with.
• text field split up into header_text and body_text.
• genre: The genre of the post (ex: General, Relationships).
• year_of_study (optional): The year of study of the poster (ex: One, PhD, Graduate).
• faculty (optional): The faculty of the poster (ex: Engineering, Arts).
• associated_with_user: Determines if the user wants this post to be easily findable from their private profile, or if they want it completely disassociated with them.

Auto-applying tags

• Adds a new field tags: Vec<&'static str> to the Detail type.
• This field is then auto-populated with tags based on certain attributes of a Post.

Documentation

• Docs for GET /posts/ and POST /posts/ updated to match newly updated Post fields.

[mattrltrent]

Closes #24 and closes (technically frontend so no link) #32.