feat: create table through GRPC interface (#224)

* feat: create table through GRPC interface

* move `CreateExpr` `oneof` expr of `AdminExpr` in `admin.proto`, and implement the admin GRPC interface

* add `table_options` and `partition_options` to `CreateExpr`

* resolve code review comments

Co-authored-by: luofucong <luofucong@greptime.com>

src/datanode/src/sql/create.rs

@@ -150,6 +150,7 @@ impl<Engine: TableEngine> SqlHandler<Engine> {
             schema,
             primary_key_indices: primary_keys,
             create_if_not_exists: stmt.if_not_exists,
+            table_options: HashMap::new(),
         };
         Ok(request)
     }