Actually make PackageManagerInternal things internal

There are a few methods that were still relying on the bound caller id
instead of acting as an internal call. This change extracts the ones
necessary to get webview resolution working correctly.

Bug: 142386643
Test: atest WebViewHostSideStartupTest
Change-Id: I1aa80d5c9f8308fef42ffa4901c1114a2e5cd9e9