[prism] Support Gauge Metrics

[lostluck]

Similar to #31927, but implement Gauge Metrics.

A metric accumulator will need to be added for the type in prism:

https://github.com/apache/beam/blob/master/sdks/go/pkg/beam/runners/prism/internal/jobservices/metrics.go#L357

And adding the type to the accumulator factory list:

https://github.com/apache/beam/blob/master/sdks/go/pkg/beam/runners/prism/internal/jobservices/metrics.go#L168

Specifically with the right URNs and coders:

https://github.com/apache/beam/blob/master/model/pipeline/src/main/proto/org/apache/beam/model/pipeline/v1/metrics.proto#L520

Once unfiltered, this will allow the following Java Validates Runner tests to pass.

MetricsTest.testCommittedGaugeMetrics
MetricsTest.testAttemptedGaugeMetrics