Use TagType constants

Now that the aidl compiler supports it, use constants from TagType to
indicate the type of each tag, rather than duplicating the values of
the constants.

Test: atest VtsAidlKeyMintTargetTest
Bug: 183737811
Merged-In: Ie8af1f00d04fa05c59cfc72692caecbcf2fae483
Change-Id: Ie62b6ee8a8ced05a870711073bb3be16931f3d4d