add comments funcionality (not merge)

[isaul19]

• dynamodb models of "Comment" and "PostComments".
• created ui for comments
• the functionality to create comments and save them in the db was created.
• 1 comment is shown by default, but you can see up to the last 10 comments.
• the response is missing based on the gpt api.

[albac]

This looks good, but I think we need to add the semantic search so it can look at the documents. This can be merge now and we can create another ticket for it.