[Feature Request][Go SDK]: Allow setting Log Level for pipelines.

### What would you like to happen?

The SDK isn't able to specific log levels to filter down into at the present time (noted by Dataflow documentation https://cloud.google.com/dataflow/docs/guides/logging#SettingLevels at least).

This can cause cost overruns or exess logs being filtered from backends like Cloud Logging.

The SDK should be able to set the minimum log level with a flag, or a programmatic option, like via the `harnessopts` package used for SideInputCache capacity, or for setting sampler frequency or heap dumps:

https://github.com/apache/beam/blob/master/sdks/go/pkg/beam/util/harnessopts/sampler.go

https://github.com/apache/beam/blob/master/sdks/go/pkg/beam/util/harnessopts/heap_dump.go

### Issue Priority

Priority: 2 (default / most feature requests should be filed as P2)

### Issue Components

- [ ] Component: Python SDK
- [ ] Component: Java SDK
- [X] Component: Go SDK
- [ ] Component: Typescript SDK
- [ ] Component: IO connector
- [ ] Component: Beam examples
- [ ] Component: Beam playground
- [ ] Component: Beam katas
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- [ ] Component: Spark Runner
- [ ] Component: Flink Runner
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- [ ] Component: Twister2 Runner
- [ ] Component: Hazelcast Jet Runner
- [ ] Component: Google Cloud Dataflow Runner