Retry command on TPM_RC_RETRY

Certain TPM2 commands are allowed to return TPM_RC_RETRY when the client should attempt the command again. This has caused some problems in higher level applications (see https://github.com/google/go-tpm-tools/pull/1) and in other TPM libraries (see https://github.com/tpm2-software/tpm2-tools/issues/469).

It would be nice if runCommand simply checked for TPM_RC_RETRY and reissued the command automatically, this would also help avoid having to add code higher up the stack like [this C library had to do](https://github.com/tpm2-software/tpm2-tools/pull/585/files#diff-5c58d23d240af6c75eebbdea9fef670b).