Extend ClickHouse source model with deletable flag

- Add `IsDeleteable` field to `ChSource` struct
- Implement `IsDeleteable()` method for `ChSourceWrapper`
- Add `ToSinkParams()` method to create a copy of source with deletable flag set to false by default

pkg/providers/clickhouse/model/model_ch_source.go

@@ -53,6 +53,7 @@ type ChSource struct {
 	BufferSize       uint64
 	IOHomoFormat     ClickhouseIOFormat // one of - https://clickhouse.com/docs/en/interfaces/formats
 	RootCACertPaths  []string
+	IsDeleteable     bool
 }
 
 func (s *ChSource) Describe() model.Doc {
@@ -346,3 +347,17 @@ func (s ChSourceWrapper) SetShards(shards map[string][]string) {
 		})
 	}
 }
+
+func (s ChSourceWrapper) IsDeleteable() bool {
+	return s.Model.IsDeleteable
+}
+
+func (s *ChSource) ToSinkParams() ChSourceWrapper {
+	copyChSource := *s
+	copyChSource.IsDeleteable = false // По умолчанию false для source
+	return ChSourceWrapper{
+		Model:    &copyChSource,
+		host:     "",
+		altHosts: nil,
+	}
+}