[Feature request] Ability to provide the initial side

[vladmircan]

Currently, all Flippables start out facing with the front side.

I have encountered a scenario in which it would be desirable to specify which side should be shown first (front or back).
This could be achieved by adding a parameter to the rememberFlipController() and the corresponding FlippableController constructor.

Of course, I can conditionally specify the composables of the front/back sides but that is nothing more than a workaround and it adds unnecessary complexity that has to be managed.

Thanks!