feat: add ability to configure custom database connection

[patressz]

This pull request includes several changes to the DatabaseAnalyticsRepository and PanConfiguration classes to enhance database connection handling. The most important changes include updating the constructor and methods in DatabaseAnalyticsRepository to use the DatabaseManager for database operations, and adding methods to PanConfiguration for setting and getting the database connection.

Enhancements to database connection handling:

• Updated the constructor to inject DatabaseManager and replaced direct DB facade calls with $this->connection() method to use the configured database connection.
• Added a private connection() method to resolve the database connection using the configuration.

PanConfiguration:

Added a databaseConnection property and methods to set and get the database connection.

Unit tests:

• Added a test to verify the databaseConnection can be set and retrieved correctly.