Improve submission status for new responses

[dtonon]

Following up #233 (Replies don't show up immediately) I propose a new UI to show the posting/posted status of a note. The note is placed in the correct position on the thread and the bottom bar is replaced with a loading animated component:

After the submission procedure ends the summary is displayed on the same bar, on the left a buttons permit to see the details (current bottom sheet modal):

The bar can be replaced after a certain amount of time (ex. 30 seconds) or if the note receives an event (reply, reaction, zap).

[dtonon]

We should probably add the case of an unsuccessful submission (e.g. network error) or one with a high percentage of missing relays, giving the user the option of retrying the submission with a click.