bootstat: add support for regex in aliasReasons and powerkeys

Add support for regex in aliasReasons for the alias member.  Use this
new feature to check powerkey|power_key|PowerKey for a single entry.

Test: boot_reason_test.sh
Bug: 63736262
Change-Id: Ia6add99b9e33f3197643dbaab88dde20aa726f90
2 files changed