Add query to return a list of available queries for the workflow instance

[mfateev]

The list should also include documentation about each query semantic and accepted arguments.

[dmetzgar]

Cadence Web is actually working around this by attempting to call a query and parsing the list of names from the returned error. It doesn't include the parameters though.

[mfateev]

And it is broken for Java which returns this list in a different error string

[demirkayaender]

this should already be supported, closing it.