[FEATURE] The table fields of a JDBC type data source need to support JSON field types.

### Describe the feature

The number of JDBC data source types supported by Gravitino is increasing, and most of the current JDBC data sources support JSON type fields. This is also a commonly used field type in business. Do you have plans to support JSON field types in the community?

### Motivation

_No response_

### Describe the solution

_No response_

### Additional context

_No response_

No files, tests, or entry points are named. Start by locating the JDBC data-source type mappings and reviewing how table fields are represented for the currently supported sources. Done should mean JSON field types are supported consistently across the relevant JDBC data sources, with coverage verified by the existing tests.

Written by the indexing model from the issue text.