Add a user comments section in the job view page

[mosmuell]

You might want to store some comments on a specific job that you have run to remember or share your thoughts. Adding a simple comments section to each job view would help with that. There is no need for reply functionality or anything of that kind. A simple box where you can add some notes suffices.
The data should be stored in the HDF file s.t. it can be shared with the data.

• Backend
  • Create new dataset in HDF file for comments
    • One row for each comment
  • Add api functions to add / delete / retrieve comments
    • Broadcast changes (using emit_queue)
• Frontend
  • Get comments from HDF file when loading job page
    • If the file does not exist, there are no comments. Once the file is created, new comments are broadcasted, so we won't miss any
  • Add comments section component, displaying all the comments along with their timestamps
    • Like a chat, you can add or delete comments