Add support for get_relations_by* / get_tables_by* using information_schema in Unity Catalog

[tfayyaz]

Databricks and Unity Catalog now supports information_schema https://docs.databricks.com/sql/language-manual/sql-ref-information-schema.html and so it should now be possible to support some of the missing shims listed in the readme and as one of the tasks in #7:

The missing shims are:

• dbt_utils.get_relations_by_prefix_sql
• dbt_utils.get_tables_by_pattern_sql
• dbt_utils.get_tables_by_prefix
• dbt_utils.get_tables_by_pattern

I will be willing to try and contribute these but will need guidance on how to define the logic that only allows these to be compatible if you are using >=dbt-databricks==1.1.1 and have Unity Catalog enabled.

Thanks
Tahir