Describe requested visibilities in public types (2/n: client-server)

This CL makes the client send an integer (instead of InsetsVisibilities)
as the requested visible types to the server.

This CL also removes the usages of InsetsVisibilities from WM shell.

Bug: 253420890
Bug: 234093736
Test: atest ActivityRecordTests DisplayContentTests InsetsPolicyTest
      InsetsStateControllerTest WindowContainerInsetsSourceProviderTest
      WindowLayoutTests WindowManagerServiceTests WindowStateTests
      WindowAddRemovePerfTest StartingSurfaceDrawerTests
      TaskSnapshotWindowTest
Change-Id: I29d245e3c36a29f01bdd3347fe858727c3540ff8