Add shouldBeSeamless to setFrameRate

This CL adds a new parameter shouldBeSeamless to the existing
setFrameRate APIs. This parameter indicates whether the desired
refresh rate should be achieved only seamlessly or also switches
with visual interruptions for the user are allowed. The default
value of the new parameter is "true".

Test: atest RefreshRateConfigsTest
Test: atest SetFrameRateTest
Test: atest libsurfaceflinger_unittest
Test: atest libgui_test

Bug: 161776961
Change-Id: I0df16e09f77c8c198fd3733fb581a2aaadfed685