state/kvindexer: associate event attributes with events (#9759)

* Updated event sequencing and added query keyword

* code cosmetics

* Documentation update

* Added per event indexing and querying to txindexer

* rpc test fix

* Added support for older versions where event sequencing is not supported

* Added support for old versions to tx indexer

* Added RPC match flag, fixed bugs in tx indexer, added tests

* Removed reference to match.events from the docs

* Openapi update

* Added height deduplication
Co-authored-by: Thane Thomson <connect@thanethomson.com>

Co-authored-by: Anca Zamfir <zamfiranca@gmail.com>
Co-authored-by: Sergio Mena <sergio@informal.systems>
Co-authored-by: Romain Ruetschi <romain.ruetschi@gmail.com>
Co-authored-by: Thane Thomson <connect@thanethomson.com>

types/events.go

@@ -140,6 +140,11 @@ const (
 	// BlockHeightKey is a reserved key used for indexing BeginBlock and Endblock
 	// events.
 	BlockHeightKey = "block.height"
+
+	// MatchEventsKey is a reserved key used to indicate to the indexer that the
+	// conditions in the query have to have occurred both on the same height
+	// as well as in the same event
+	MatchEventKey = "match.events"
 )
 
 var (