feat: add bigquery execution project params

[xxntti3n]

Add execution_project parameter to BigQuery data source to
support separate billing projects for query execution.

Motivation

When running data quality checks against multiple BigQuery
projects, organizations often want to:

• Centralize query costs to a single billing project
• Track Soda Core costs separately from data project costs
• Use a service account with billing access in a central
  project

[CLAassistant]

All committers have signed the CLA.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[xxntti3n]

Hi @m1n0
I've added a new execution_project parameter to the BigQuery connection properties. This is useful when your authentication project and query execution/billing project are different.
Let me know if you'd like me to adjust the tone or add more details!