Add PccSandboxManager and PccSandboxManagerService classes

Adding new system service PccSandboxManagerService which should manage
interactions between apps and pcc components.

Adding getPccEntities which should return entities (apks/services)
that should be running in the pcc sandbox.

context: go/pcc-apk

Test: atest PccServicesTests & atest CtsPccManagerTestCases
Flag: android.app.privatecompute.flags.enable_pcc_framework_support
Bug: 430201829
Bug: 437280042
Change-Id: Ib15877db74966469b49ea0223a9b3ca714877efa