Pass vault name and requested password type to askpass process

[tgyurci]

Closes #155

[miquella]

Thanks for taking a pass at this, I think it's a good start!

A couple of things that I think could be improved:

• The VAULTED_PASSWORD_TYPE should probably be a smaller set of values (e.g. MFA token, password, and maybe legacy password; legacy could be captured as part of the disposition below)
• The disposition/reason for the password should be separate from the password type (e.g. confirmation, passwords didn't match, etc.)
• These values should be enumerated as const values at the top of steward.go
• The possible values should be enumerated in the man page

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I apologize that it's taken me a while to get back with you, so I understand if you don't have time to continue this work. If you don't have the time, I'll see if I can wrap it up next time I have some time to devote here. 😀

[tgyurci]

I modified the change to match your suggestions. I'm open to any comment especially about the current password type and reason values.