[SystemUiController] Add Dialog and custom Window support

[alexvanyo]

This PR adds an optional, nullable Window parameter to rememberSystemUiController.

The default value of this parameter is a multi-step fallback:

• First, the Window will be pulled from the DialogWindowProvider (if available), which will return the Window corresponding to a Dialog managed by Compose.
• Second, the Window will be attempted to be retrieved from the Activity (which matches current behavior).
• Third, return null.

If both methods fail, then no Window will be available, and systemUiController will degrade in behavior (which is useful for @Preview usage).

Additionally, a specific Window can be passed directly as an argument, which is useful in cases where the default behavior will fail (for example, if a ComposeView is being used inside of a Dialog or a DialogFragment)

I added a new Dialog sample to showcase the new behavior, and the remainder of this PR's content is tests.

This fixes #1110

[bentrengrove]

LGTM! Nice work