Made some class templates for code that seemed duplicated between
file/protocol tags and managers. Seems like it helps a bit and
hopefully can be also be used to transition other things that have
enum value "tags" (e.g. logging writers, input readers) to the
plugin system.
This cleans up internals of how analyzer instances get identified by the
tag plus any args given to it and doesn't change script code a user
would write.
