miscellaneous SVSM support fixes

#600 introduces usage of direct tpm2 interface. This includes the addition of makeAK(), ekPub(), and ekPolicy(). These are duplicate to the structures defined in template.go and keys.go. When we transition go-tpm-tools to use direct tpm2 interfaces, we should make sure to remove these extraneous helpers in client/import_certify.go

Start with #600, then compare the duplicate makeAK(), ekPub(), and ekPolicy() helpers in client/import_certify.go with their definitions in template.go and keys.go. Confirm the direct tpm2 transition context and remove only the extraneous helpers; done means the duplicate definitions are gone without losing the existing functionality.

Written by the indexing model from the issue text.