Actually export quiche_file_utils test files.

Also add a WHITESPACE file similar to what Chromium and similar projects have.

PiperOrigin-RevId: 446501308

WHITESPACE

diff --git a/WHITESPACE b/WHITESPACE
new file mode 100644
index 0000000..91b7478
--- /dev/null
+++ b/WHITESPACE
@@ -0,0 +1 @@
+Edits in this file will cause a Copybara migration.
\ No newline at end of file