Tar stream reader test fixtures

USTAR-format .tar files used by tarStreamReader.test.ts. Generated with tar --format=ustar (macOS bsdtar and GNU tar support this). On macOS, COPYFILE_DISABLE=1 is set in the script to avoid AppleDouble ._* entries.

To regenerate:

bash

./apps/dotcom/sync-worker/src/utils/tarStreamReader-fixtures/generate-fixtures.sh

Then commit the updated .tar files.