Fix annotation state not being updated when annotations are saved

[robertknight]

Annotations in the app's local state store were not being updated
after a save was successfully committed on the server.

Fixes hypothesis/h#2965

[robertknight]

[Bug] Annotation search does not find edits made in current session #2965

[seanh]

Noticed two problems:

1. If I do a search and an annotation matches the search, and then without clearing the search I edit the annotation so that it no longer matches the search, the annotation disappears. Things vanishing when you hit save seems bad. I'd say any annotation that matched the search at the time when the search was first made should remain in the search results, until the search query is changed, even if edits to the annotation mean that it no longer matches the search. I'm not sure whether the current behaviour is as it used to be on master though?
2. If a search has no matches an empty string is rendered: No results for “”. This is also on master though, will open a separate issue.

[seanh]

Alright, I think the two above are pre-existing issues, this pr fixes another issue where the annotation contents would revert to the previous contents on clearing a search etc. Merging this

[seanh]

Opened issues for the two pre-existing problems found above: #9 and #10