Add data source to poll IHealth (battery counters) service

This CL adds a new "power" data source to poll battery
counters (AKA Coulomb counters) from the perfetto
traced_probes service. Doing so requires making HWBinder
transactions on the Android IHealth service. This has two
drawbacks: (1) the IHealth svc and hwbinder are internal
only and not part of the NDK; (2) using hwbinder requires
pulling 6 .so(s), which adds 150 KB of private dirty memory
due to linker relocations.

Both aspects are solved as follows:
1) libperfetto_android_internal.so is loaded/unloaded
   dynamically to access the the hwbinder, loading
   recursively libhwbinder.so etc.
3) In standalone builds, libperfetto_android_internal.so
   will not be found and the power data source will
   gracefully fail.

This CL depends on SELinux CL aosp/838610.

Bug: 113076327
Change-Id: Ice56c79bb1c8eec051f6c5d0afec01570a76a0a4
diff --git a/src/traced/probes/BUILD.gn b/src/traced/probes/BUILD.gn
index fd01252..17fe4db 100644
--- a/src/traced/probes/BUILD.gn
+++ b/src/traced/probes/BUILD.gn
@@ -39,6 +39,7 @@
     "../../tracing:ipc",
     "../../tracing:tracing",
     "filesystem",
+    "power",
     "ps",
     "sys_stats",
   ]