New module type to collect cert files for otatools.zip

- Use finder.go to search "*.pem", "*.pk8", and "*.avbpubkey".
- The "otatools_package_cert_files" gathers these certs into zip.
- The cert files are in "build/make/target/product/security", "device",
  "external/avb/test/data", "packages/modules", and "vendor" folders.

Bug: 403277238
Test: m -j blueprint_tools && cat out/.module_paths/OtaToolsCertFiles.list
Test: m otatools_package_cert_files
Change-Id: I5673ef03b0e47c7783918f566af67c1fdc2838bb
diff --git a/android/Android.bp b/android/Android.bp
index 00dc50a..71e6747 100644
--- a/android/Android.bp
+++ b/android/Android.bp
@@ -83,6 +83,7 @@
         "nothing.go",
         "notices.go",
         "onceper.go",
+        "otatools_package_cert_zip.go",
         "override_module.go",
         "package.go",
         "package_ctx.go",