feat(go): implement URI parsing logic and add tests

[Mandukhai-Alimaa]

What's Changed

• Add BigQuery URI parsing: Accept URI format connection strings (bigquery://[host]:[port]/project?param=value) and parse them into driver options
• Add endpoint override support: Support custom BigQuery endpoints with proper host/port handling
• Add tests.

[Mandukhai-Alimaa]

@lidavidm can't seem to request feedback, so tagging here.

[lidavidm]

Tested locally, LGTM