Deprecate `runningWorker` and add `@ReplaceWith` for `runningSideEffect` alternative

[blvckbox]

There is a variant of runningWorker for when your Worker doesn't output anything. The kdoc mentions to use runningSideEffect as the alternative. We should consider a formal @Deprecation of this runningWorker API and can use @ReplaceWith for in-place fix/migration.

Not sure how this type of thing is handled but could then add warning in the deprecation message that this API will be removed in future version

[steve-the-edwards]

Completely removed by #1237