Record date pin was added

Description of the new feature / enhancement

As a user, I'd like to be able to periodically audit my pins. Project needs change over time. It may be possible that at one point a project required a specific version of a package, but then later added support for newer versions of the same package. This typically doesn't happen overnight which means that I probably won't be able to remember when I first added the pin. So, every time I want to audit the packages I have pinned, I have to go through every single one rather than ones that are older than say . . . 6 months.

It would be extremely useful to be able to see the date a pin was added so when I audit my pins, I can skip ones which are only a month or two old.

• Related to #3212

Proposed technical implementation details

Also show the date in winget pin list

Start at the winget pin list command and inspect how pins are represented and persisted. Confirm the intended date semantics with related issue #3212, then add the date a pin was added to the list output and cover the displayed date with tests.