Trace Redaction - Create foundation for trace redaction

In order to set-up the foundation for migrating the trace redaction work
into the Perfetto repo, the following three work items had to be
executed together.

1. Set-up directory and build files for future work
2. Define key data types (context + primitive)
3. Define execution pattern

To demonstrate how everything works, this implements primitives
that find a target package in the package list and removes all
other packages.

Bug: 318576092
Change-Id: I5fca1102abc6bb02e433453817c56270023368e2
diff --git a/gn/perfetto_unittests.gni b/gn/perfetto_unittests.gni
index 2769a63..f1d46ba 100644
--- a/gn/perfetto_unittests.gni
+++ b/gn/perfetto_unittests.gni
@@ -85,3 +85,5 @@
 if (enable_perfetto_traced_relay) {
   perfetto_unittests_targets += [ "src/traced_relay:unittests" ]
 }
+
+perfetto_unittests_targets += [ "src/trace_redaction:unittests" ]