Update the process of specifying/creating now (runtime provided datetime)

[sl-slaing]

Feature request

A profile can specify now as a 'dynamic' value for production; however this cannot be used with any other date-time granularity. As shown in #1706 any attempt to do so will either yield no data or report a contradictory profile. Consider either:

• Adding a today value provider (equivalent to now but produces values granular to Days rather than Milliseconds)
• Changing the method of producing now so it can be combined with different granularities, i.e. granular to Years, Months, etc. from the current run time.