Add Basic Auth as an authentication option for the Prometheus connector

Problem

The Prometheus connector currently supports only bearer token authentication (prometheus.bearer-token-file). Prometheus v2.24.0+ natively supports HTTP Basic authentication via a web config file, but there is no way to configure the Presto connector to send Basic Auth credentials.

This blocks connecting to any Prometheus instance that is secured with Basic Auth instead of a bearer token.

Upstream reference: trinodb/trino#12302

Proposed Solution

Add two new optional config properties to PrometheusConnectorConfig:

Property	Description
prometheus.auth.user	Username for Basic authentication
prometheus.auth.password	Password for Basic authentication

Behaviour:

• Both properties must be set together or not at all (startup fails otherwise)
• Cannot be combined with prometheus.bearer-token-file (startup fails)
• Username must not contain :
• Bearer token behaviour is unchanged for existing catalogs