feat: configure keystore parameters with environment variables

[lenkan]

This PR enables you to configure which keystore to access using environment variables.

Summary of changes:

• Extracted --name, --base and --passcode into a common "Parsery.keystore()" method. Not sure about the module or naming here, tried to follow https://github.com/WebOfTrust/keripy/blob/main/ref/naming.md, but please advise. Should be easy search replace to modify.
• Removed redundant "transferable=True" default option which seemed to have been left over from copy-paste. Please advise if not correct and I can change back.
• Inlined the "addInceptingArgs" as it was only used in one place. I thought we could define one pattern for common arguments and use that everywhere.

Closes #955

[lenkan]

I believe the failed windows tests are fixed by #986

[lenkan]

Note that if you are hesitant about the environment variables being enables, we can disable it. It is trivial to add now when the keystore parameters are extracted to its own module. We can also hide it being a feature flag.