picky-krb: CredSSP credentials structures

[TheBestTvarynka]

Hello,
During the Kerberos smart card logon, the smart card credentials are transferred using the TsSmartCardCreds and TsCspDataDetail structures.

The password-based credentials are encoded using the ber module in the sspi-rs. But now we have picky-* crates for the asn1 encoding. So, I decided to add CredSSP-related constants and credentials structures to the picky-krb crate.

Docs and reference:

• TSCredentials
• TSPasswordCreds
• TSSmartCardCreds
• TSCspDataDetail

[CBenoit]

This is looking good to me!

I see you authored a rather clean history on your branch so if you want, we can "rebase and merge" the PR, but there is small details I want fixed by rebasing interactively first:

• The commit adding tests should either be part of the commit adding the feature, or alternatively the conventional commits type "test" should be used instead of "feat"
• We don’t really scope commits by module
• We don’t end the summary with ;
• The summary line should be no longer than 50 characters (and at the very most 72 characters), so that it doesn’t get wrapped onto the next line like here:
  
• Rebase interactively my "suggestion commit" into the relevant commit (using the fixup rebase command)

This would give the following history:

• feat(picky-krb): add credssp password and smartcard structs
• feat(picky-krb): add creds and key spec constants
• test(picky-krb): unit tests for credssp structs
• feat(picky-asn1-x509): add USER_PRINCIPAL_NAME oid

Following this convention helps me when generating the changelogs.

Otherwise I usually squash the whole PR into a single commit for simplicity.

[TheBestTvarynka]

@CBenoit
Changed commit messages according to your guideline. I'll keep it in mind for future commits.

[CBenoit]

Thank you! @TheBestTvarynka
I’ll rebase and merge into master 😄
FYI, I’m wrapping up some other work after what I’ll cut a release for a few picky crates.