feat: add explain options to query request (#225)

* feat: add verbose flag

* feat: use options for explain

* chore: generate codes

proto/greptime/v1/common.proto

@@ -27,6 +27,8 @@ message QueryContext {
   map<string, string> extensions = 5;
   uint32 channel = 6;
   SnapshotSequences snapshot_seqs = 7;
+  // Explain options for the query.
+  ExplainOptions explain = 8;
 }
 
 message SnapshotSequences {
@@ -36,6 +38,11 @@ message SnapshotSequences {
   map<uint64, uint64> snapshot_seqs = 7;
 }
 
+message ExplainOptions {
+  // Whether to enable verbose explain output.
+  bool verbose = 1;
+}
+
 message RequestHeader {
   // The `catalog` that is selected to be used in this request.
   string catalog = 1;