built-in query for waiting signals to go-sdk

[zengzilu]

Is your feature request related to a problem? Please describe.
I need to known what signal can I send to a running flow, some signal might block the flow, some might change the flow running. when the flow doesn't behave as I supposed, I need to check the signals

so there is the issue: request a built-in query for waiting signals

Describe the solution you'd like
A clear and concise description of what you want to happen.

Describe alternatives you've considered
mark all signal with workflowOutboundInterceptor GetSignalChannel and query it, but it's not exactly what I need, because the signal might has been signed, it is not a "waiting signal". it means all signals that happened to the flow. what I exactly need is "waiting signals" which means what can I send to the flow now

Additional context
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[cretz]

This is something we're planning on doing one day, see temporalio/features#51.

In the meantime, you can provide your own query to provide your own information to your caller.

[Quinn-With-Two-Ns]

closing as it is effectively a duplicate of temporalio/features#51