Duplicate definition of data type in PostgreSQL/openGauss BaseRule.g4

## Refactor

The `dataType` was custom:
https://github.com/apache/shardingsphere/blob/795d3721d648c1ede9f839273b80ee14d89d6ff9/sql-parser/dialect/postgresql/src/main/antlr4/imports/postgresql/BaseRule.g4#L1464-L1477

The `typeName` was the same as PostgreSQL's grammar:
https://github.com/apache/shardingsphere/blob/795d3721d648c1ede9f839273b80ee14d89d6ff9/sql-parser/dialect/postgresql/src/main/antlr4/imports/postgresql/BaseRule.g4#L1075-L1220

https://github.com/postgres/postgres/blob/d952373a987bad331c0e499463159dd142ced1ef/src/backend/parser/gram.y#L13907-L14363

These definitions were used in different syntax. Maybe we should consider unifying the definition of data type?

Compare the custom dataType rule and the existing typeName rule in sql-parser/dialect/postgresql/src/main/antlr4/imports/postgresql/BaseRule.g4 with the corresponding PostgreSQL grammar in gram.y. Trace where each rule is used, then determine whether they can be unified without changing the distinct syntax they currently support; done means the duplicate definition is resolved and parser behavior remains covered.

Written by the indexing model from the issue text.