Expand relational grammar to allow dashes in schema names

[epsstan]

Feature Request

Expand relational grammar to allow dashes in schema names.

Description of Problem:

In some databases/dataservices (e.g BigQuery), the schema name does not allow "_" (underscore) but does allow "-" (dash).

Using "-" in a schema name results in a compilation error.

Potential Solutions:

The grammar defines "schema" to be an "identifier" [1]. "identifier" does not include dash (-). The grammar should be change to include "-" (dash) for schema names.

[1] https://github.com/finos/legend-pure/blob/master/legend-pure-m2-store-relational/src/main/antlr4/org/finos/legend/pure/m2/relational/serialization/grammar/v1/antlr/RelationalParser.g4#L21