Give symbolize-buildbot-crashes.sh the ability to read from a file.

symbolize-buildbot-crashes.sh would always read from adb logcat.
Sometimes it is useful to read from a file though. This change lets
the crash logs be given as the first argument.

Test: manual
Bug: 74429665
Change-Id: Idd09e8eb5117082c98860e98b9e8afa05fe83e77