Feature: Add Vault Auth as a flag

[reskin89]

It would be nice to have a flag to allow buildenv to fetch a vault token/auth to vault when invoked

[vorbidan]

@reskin89 - do you mean to add an authN option to buildenv cli, something like buildenv login -url=?

[reskin89]

Something such as -a OPTIONS, so if you don't have a vault token you can acquire one via either oidc or with a role and secret id as with an app role.

This would allow a short lived (2 minute?) token for the duration of the buildenv invocation.

Essentially fetch a token for the invocation of buildenv, and I guess potentially, decom the token at the end