Add stateful filesystem scanner.

This will be used to interrupt long scans.

Bug: 74584014
Change-Id: I80206a3dd6cce265fc957532c855f07f08120a7d
diff --git a/Android.bp b/Android.bp
index b9c1996..953276c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -63,6 +63,7 @@
     "src/protozero/proto_utils.cc",
     "src/protozero/scattered_stream_null_delegate.cc",
     "src/protozero/scattered_stream_writer.cc",
+    "src/traced/probes/filesystem/file_scanner.cc",
     "src/traced/probes/filesystem/fs_mount.cc",
     "src/traced/probes/filesystem/inode_file_data_source.cc",
     "src/traced/probes/filesystem/lru_inode_cache.cc",
@@ -301,6 +302,7 @@
     "src/protozero/proto_utils.cc",
     "src/protozero/scattered_stream_null_delegate.cc",
     "src/protozero/scattered_stream_writer.cc",
+    "src/traced/probes/filesystem/file_scanner.cc",
     "src/traced/probes/filesystem/fs_mount.cc",
     "src/traced/probes/filesystem/inode_file_data_source.cc",
     "src/traced/probes/filesystem/lru_inode_cache.cc",
@@ -3340,6 +3342,7 @@
     "src/protozero/scattered_stream_writer_unittest.cc",
     "src/protozero/test/fake_scattered_buffer.cc",
     "src/protozero/test/protozero_conformance_unittest.cc",
+    "src/traced/probes/filesystem/file_scanner.cc",
     "src/traced/probes/filesystem/fs_mount.cc",
     "src/traced/probes/filesystem/fs_mount_unittest.cc",
     "src/traced/probes/filesystem/inode_file_data_source.cc",