Provide onMinimized alternative right after minimization click

[diklimchuk]

Is your feature request related to a problem? Please describe.
There's a problem that we need to distinguish between custom tabs flow cancellation and custom tabs minimization. We detect that in onResume. However onMinimized callback is invoked 1 second after onResume which delays app reaction to minimization event and requires handling of use cases when the user clicks on something in that 1 second. Basically the problem is that we don't know that custom tabs are being minimized right away.

Describe the solution you'd like
A callback like onStartMinimization which will be invoked when a user clicks on the minimize button