Get rid of synchronization.debounce and use _.debounce instead

[baaygun]

After realizing that in Mar 19, 2015, we got rid of the async waiting nature of our own debounce function, and it's identical to _.debounce, this cleans it up so we use lodash.

Addresses #3639, @iwehrman please review. @mcilroyc it would be nice to have your eyes on this, as well.

[mcilroyc]

I've never believed that using debounce with a wait of zero was a reasonable thing to do ... or least that it is never what we want to do in design space. Now may be as good a time as any to argue about this. There's only a couple of places that still provide no explicit wait value (thus defaulting to zero).

[mcilroyc]

I suppose I forgot to mention: this all looks correct to me as a direct refactoring. I guess we never used the "immediate" feature which would have been equivalent to the the "leading" lodash option. Just saying that out loud.

[baaygun]

@mcilroyc @iwehrman Thank you for reviews. I've cleaned up the actions code so we no longer have debounced suffix, and also the untimed debounce call for artboard Transform handler.

[iwehrman]

LGTM, thanks!