#998: Added GET.UNWATCH command support and fix watch related issues

[psrvere]

Closes #998

Changes

1. Implemented GET.UNWATCH command in RESP server with integration tests.
2. Updated Dice SDK version to fix a minor bug

Bug Fixes

1. Fixed panic in GET.WATCH command when called without arguments
2. Fixed premature fingerprint deletion in handleUnsubscription function (watch_manager.go). This prevented execution of the next cleanup block.
3. Corrected cmdWatchSubscriptionChan initialisation that was incorrectly set to nil in PR Changed scope of CmdWatchSubscriptionChan to local #1169

[psrvere]

@JyotinderSingh - Please reivew.

[JyotinderSingh]

Thanks for working on this @psrvere! I believe there is a slight misunderstanding on how the command works. I've explained it in my other comment. I don't think it will take too much effort to make that change.

[JyotinderSingh]

Thanks for the quick resolution to the comments @psrvere! The changes look and well tested. Thanks for making the required SDK changes too.

Approved!