Unified Storage: Add ListSinceModified to StorageBackend (#109697)

* WIP added ListSinceModified to StorageBackend interface

* fix compile time check

* Fix method name

* Fix naming

* fix the rest of the ListSinceModified names

* Uses resource key without name field

* get latest rv from resource_version. Update test.

* adds moar tests

* adds method stub for ListModifiedSince to other StorageBackend implementations

* adds dummy impl to noop storage backend for ListModifiedSince

* skip tests for badger kv backend for now

* fixes tests and adds badgerkv impl for ListModifiedSince

* add badger kv impl

* adds test for new query

* adds test data for new query

* adds ListModifiedSince stub to mockStorageBackend

* uncomment tests

* refactors ListModifiedSince to return an iter.seq2 and handles deduplication. Updates tests. Updates query result sorting.

* remove comments

* remove folder from query (dont need it, yet?)

* regen test queries

* updates test

* updates function comment

* use resourcepb.ResourceKey instead of ModifiedResourceKey

* wrap seq in single transaction. Rollback transaction after 30s if iterator never used. Only track last seen event. Formatting.

* skip TestListModifiedSince for kv backend

* use WatchEvent_Type for action type

* remove redundant fields from order by clause and regen test data for query

* remove redundant fields from order by clause and regen test data for query

pkg/storage/unified/resource/server.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"iter"
 	"log/slog"
 	"net/http"
 	"sync"
@@ -114,6 +115,10 @@ type StorageBackend interface {
 	// ListHistory is like ListIterator, but it returns the history of a resource
 	ListHistory(context.Context, *resourcepb.ListRequest, func(ListIterator) error) (int64, error)
 
+	// ListModifiedSince will return all resources that have changed since the given resource version.
+	// If a resource has changes, only the latest change will be returned.
+	ListModifiedSince(ctx context.Context, key NamespacedResource, sinceRv int64) (int64, iter.Seq2[*ModifiedResource, error])
+
 	// Get all events from the store
 	// For HA setups, this will be more events than the local WriteEvent above!
 	WatchWriteEvents(ctx context.Context) (<-chan *WrittenEvent, error)
@@ -122,6 +127,13 @@ type StorageBackend interface {
 	GetResourceStats(ctx context.Context, namespace string, minCount int) ([]ResourceStats, error)
 }
 
+type ModifiedResource struct {
+	Action          resourcepb.WatchEvent_Type
+	Key             resourcepb.ResourceKey
+	Value           []byte
+	ResourceVersion int64
+}
+
 type ResourceStats struct {
 	NamespacedResource