Add DPM EXEMPT_FROM_SUSPENSION constant

Replace app standby constant as this is no longer
needed and will be covered as part of the power
restriction exemptions

Also remove the while in user permission exemption,
this is no longer in scope.

Bug: 246330879
Test: atest ApplicationExemptionsTest
Change-Id: Ida468e99d0662c9782e5098e657285cf52090f73