[Partial Screenshare] pause mirroring when the task is in PIP

To avoid malformed transformations due to inaccurate bounds
when the task is in PIP. pause recording entirely when the
task enters PIP and resume when the task leaves PIP.

Bug: 297514518
Test: atest WmTests:ContentRecorderTests
Test: manual MediaProjection smoke tests, change windowing modes
Change-Id: I92ba7a211d0c719e60d8a397f2ba1b250903eb01