This is a preparation for accessing BPF program and map from existing
Java class. The new class ClatdTracker stores the clatd information
for forking clatd, accessing BPF maps and attaching BPF programs.
Using an object is easier to pass all required parameters and reuse
known resource.
Also refactor existing function and rename existing variables for this
commit.
Bug: 221213090
Test: atest FrameworksNetTests
Change-Id: I02ea889de89329c52710726fbcf1d2eac61707d7
328d15271b