Add `Navigator.navigateSingleTop` extension function

[arkivanov]

Add `Navigator.navigateSingleTop` extension function

[arkivanov]

@aartikov as per my comment above, this function is to ensure there is only one type of component in the stack, and to bring it to front. I suggest to use sealed classes instead of enums, or just use navigate(...) directly.

[arkivanov]

The name navigateSingleTop is misleading in this context, as it has different semantics in Android. We should find a better name. This function should work in the following way:

• If there is already a component in the stack with configuration of type T, then that component should be moved to top of the stack.
• Otherwise a new component should be created and pushed to the stack.

Some possible names: reorderToFront, makeOnTop, activate, activateOrPush, bringToFrontOrPush

[aartikov]

@arkivanov
stack.filterNot { it::class == configuration::class } + configuration

Maybe it would be better to compare values rather than classes?
Otherwise, we can't use enums for bottom navigation items.