[Improvement] Can Gravitino replace HMS?

Gravitino creates the catalog by relying on an external metastore storage system. Unlike unitycatalog, creating a catalog does not depend on other Metastores.
For example, spark + hms, replaced with spark + Gravitino, create a parquet format table:

create table demos (
id long,
name string
) using parquet

spark+Flink and Gravitino are used to store metadata, instead of relying on other table metadata such as hms, glue catalog, aliyun DLF, and jdbc.

Start by comparing the described Spark plus HMS workflow with Spark or Flink plus Gravitino, including the parquet table example and the listed metastore alternatives. Done would require a defined scope and evidence that Gravitino can provide the required catalog and metadata storage without those external metastores.

Written by the indexing model from the issue text.