[ENHANCEMENT] Allow for post + comment flagging

[SethCram]

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

• yes, users can't report content that doesn't follow site guidelines

Describe the solution you'd like

• Allow for post + comment flagging

Additional context

• worthless without [ENHANCEMENT] Add an admin account  #14 implemented first

Development

• add int flagged field to comment + post models

  • should be init'd to 0 and never negative
  • should record how many times instance's been flagged

• seems unnecessary since just the length of flags arr

• add array of flags to each post + comment model

  • each element can hold a username telling who's flagged the model

• add flag icon btn on both comment + post frontend

  • similar to vote icons
  • will be filled if user has flagged object before
    • their username will be held in the flags arr

• add api method to cast or rescind a flag

  • adds or removes an element from the flags arr