Support expiry duration in days

[yizha1]

    With the current implementation, we yet don't support `d` (e.g. `30d` ).

Originally posted by @shizhMSFT in #417 (comment)

notation sign command supports an optional expiry flag for user to specify a "best by use" time for the artifact. The duration can be specified in minutes(m) or/and hours(h). The intention of this issue is to support duration in days, for example, 30d, 1d3h20m.

[priteshbandi]

Tracking it in #129