bpfloader: move BpfLoader.cpp into Loader.cpp am: e0f11527e4

Original change: https://android-review.googlesource.com/c/platform/system/bpf/+/3208909

Change-Id: Iaff755f661bb51c9e3e09ec64850854fb3b21401
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>