tests: Check created EK cert and compare key against tpm2_createek output

Add a test case that creates various types of EKs and compares them against
the (public) keys created by tpm2_createek, if the tool is found to be
available and the swtpm tcti is installed and the tools knows how to create
the type of key. Any failure by tpm2_createek to create a key leads to no
comarison of the keys being done.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>