Add ssl_mode configuration option to allow users to customize SSL/TLS
policy for database connections instead of hardcoding sslmode=disable
for PostgreSQL and having no TLS support for MySQL.
Changes:
- database.Config, DatabaseConfig: add SSLMode field
- PostgreSQL DSN: replace hardcoded sslmode=disable with configurable
value
- MySQL DSN: append &tls=<SSLMode> parameter when SSLMode is set
- Full config pipeline: INI/env -> DatabaseConfig -> Config -> DSN ->
subprocess
- New env var BH_DB_SSL_MODE and ini key [database] ssl_mode
- Updated config example and documentation