Use the default date entry format for the default date display format

Description of the need

When a user creates a date field for a content type, they choose the date format that they would like to use. Then they add a date to a node and notice that it is displayed using a completely different format.

While this is expected behavior. The display format is currently set in the display mode, this feels very counter intuitive to me. I would expect that when I create a date field and set the format that the format would carry over to the display.

I select this as the date entry format on the field

Then I create a node and see that this is the output.

Proposed solution

When a user sets the default input format for a date field the default display format is set to match the input format.

Alternatives that have been considered

The current expectation that users will configure the input format and the display format separately is not unreasonable. I just think it's confusing for new users and that if we could create a better default behavior it would be easier for new users.

I believe that most new users are thinking about the display format when they configure the field and don't necessarily have a reason to format the input value differently from the display value. For those that do have this need, their process will pretty much remain unchanged.

I am concerned that this MIGHT be more work that it's worth and that it might open a can of worms, in terms of other date formate related assumptions that we are making. Maybe it's easier to leave this as it is.