Create a backend route that handles the POST request and stores the blog data in the database.

[krab7191]

This will be one of the most used endpoints, handling blog posts when they are created.

Acceptance criteria

• Create a POST endpoint at /api/blogpost which takes the following post body:

{
  title: string, required, validate short-ish length
  body: string, required,
  creationDate: generated on the server side, so no one can mess with it.
  author: string required, userid, pulled from user object on the backend. (current authenticated user, so can't be spoofed)
}

• Validates the above data
• Calls into a service which stores in the database and returns blogpost entry _id to the frontend.