[feature] Add from: search operator and account_id query param (#2943)

* Add from: search operator

* Fix whitespace in Swagger YAML comment

* Move query parsing into its own method

* Document search

* Clarify post search scope

internal/api/model/search.go

@@ -28,6 +28,7 @@ type SearchRequest struct {
 	Resolve           bool
 	Following         bool
 	ExcludeUnreviewed bool
+	AccountID         string
 	APIv1             bool // Set to 'true' if using version 1 of the search API.
 }