[Enhancement] Introdouce date-time and or parse_timestamp (to epoch) function (parser).

[justinmburrous]

Is your feature request related to a problem? Please describe.

We would like to have the ability to parse date-time values to epoch for comparison purposes. For example...

• Parse date-time values out of date-time fields as numbers.
• Validate that date-time values for a schedule feature in a service are x units in the future.
• Validate misc. properties on resources are at some value IF a particular resource was updated after x update-time.
• Filter versions of certain resources (where versions are represented as yyyy-mm-dd vs "v1", etc).
• Parse date-times out of fields such as Tags and or potentially Descriptions of certain resources if used in this manner.
• Validate Template parameters if used in automation and injected by automation.

Describe the solution you'd like

It would be be nice if there were a way to parse timestamps (represented as strings) in templates now into values we would use. The simplest approach would be to introduce a parse_epoch or parse_iso8601_epoch function to the existing set of functions which would enable simple numbers comparisons at the very least.

Describe alternatives you've considered

In theory all sorts of date-time functions could be supported within Guard, however a simple parser for epoch time would be a reasonable start.

Additional context

N/A for the moment.