Move multi-instance suppport checking to ApiWrapper

- It's only used for App Pairs & Taskbar (both limited to quickstep
  launcher, and we need to use hidden api to query the multi-instance
  support per-activity.  This is necessary as there can be apps
  installed for a profile, but not the primary user.

Bug: 391611065
Flag: EXEMPT bugfix
Test: atest WMShellUnitTests
Test: Install a multi-instance app only for the non-primary user,
      ensure that we can see the multi-instance UI for these apps

Change-Id: I9d38f32aa38b27b2bffaa744c3f578423f7c7d86