pw_protobuf: Add encoder_fuzzer

This CL adds a fuzzer for fuzzing the protobuf encoding. It does not try
to detect errors, ensures pushes and pops are balanced, or otherwise
hold the interface correctly. Instead these cases are ignored to fuzz
the widest possbile set of inputs.

Change-Id: Ibafa62e9420ec0285202d9a67f4f22faa827709d
diff --git a/pw_fuzzer/BUILD.gn b/pw_fuzzer/BUILD.gn
index 479fcb8..5a43021 100644
--- a/pw_fuzzer/BUILD.gn
+++ b/pw_fuzzer/BUILD.gn
@@ -37,7 +37,10 @@
 
 source_set("pw_fuzzer") {
   public_configs = [ ":default_config" ]
-  public = [ "public/pw_fuzzer/fuzzed_data_provider.h" ]
+  public = [
+    "public/pw_fuzzer/asan_interface.h",
+    "public/pw_fuzzer/fuzzed_data_provider.h",
+  ]
   sources = public
   public_deps = [ "$dir_pw_log" ]
 }