Implement RNN solver's

[BrianHarrisonAMD]

1. Description:

Currently RNNs are accessible through the public API, but they are not implemented as solvers like other operations.

[BrianHarrisonAMD]

Greetings @atamazov!

@JehandadKhan mentioned that you might be looking into implementing RNN's as solvers.
Is that accurate, and do you have any information on the status of that initiative?

Thanks in advance for any details!

[atamazov]

@BrianHarrisonAMD Status: planning, discussing. What is known is that this must be done sooner or later. I can begin doing this when time permits, but would like to discuss this with the team first.

/cc @shurale-nkn @CAHEK7 @kikimych @DrizztDoUrden

[BrianHarrisonAMD]

Thanks!