WIP: Resolve "Make timestamp modifications throughout GitLab easier"

What does this MR do?

Duplicate of !25381 (merged)

This MR adds additional settings to the user profile allowing user's to set their preference for:

• Timezone
• Absolute vs relative time (Last week vs
• 12hr vs 24hr time

The updated preferences should be available on the user's gon object

gon.user_time_settings = {
 user_time_zone: string, // (GMT -08:00) Pacific Time (US & Canada)
 user_timestamp_as_24_hours: Boolean,
 user_display_relative_time: Boolean,
}

What are the relevant issue numbers?

#57288 (closed) #56997 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer