Support PKCS11 KeyStores without keyStorePath

[sopgreg]

PKCS11 keystores as used by smart cards or HSMs don't require a keystore path. Apart from this fact, not much is different from a programmer's perspective compared to PKCS12.

Add this type to EKeyStoreType and adjust any classes like KeyStoreHelper to account for the fact of a missing keystore path.

[phax]

Thanks for the PR - I happily included it. Do you eventually have a quick link on how to easily setup the SoftHSM for testing?

[sopgreg]

For a simple start, you can install the windows package or build it yourself for linux,

https://medium.com/@purnomowhy.1981/installation-guide-softhsm2-in-windows-2e08649411c3
https://github.com/opendnssec/SoftHSMv2

The configuration is then a simple .cfg file as follows, which needs to be either referenced in JDKs java.security file or programatically via Provider#configure (as done in the unit test)

name = SoftHSM2
library = C:\SoftHSM2\lib\softhsm2-x64.dll
showInfo = true
slotListIndex = 0

via JDK: https://docs.oracle.com/en/java/javase/11/security/pkcs11-reference-guide1.html