feat: Add flag for dates to 'user event' list

Description

The command glab user events shows a list of events you've done, but it doesn't have the date information included:

❯ glab user events

Pushed new branch gmh-add-date-to-user-events at GitLab.org / cli

This can make it difficult to determine how many things have been done in a certain day (if you're monitoring your contribution count).

This MR adds a flag that will let you see the dates with each item as well:

❯ glab user events -d

2023-03-28 18:31:10.971 +0000 UTC - Pushed new branch gmh-add-date-to-user-events at GitLab.org / cli

Hey, look! That was just a minute ago! Neat!

Related Issues

Resolves #[issue_number]

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap