Template dialog UI should respect the date locale settings

> @nishantwrp sorry to reopen an old thread but I am also encountering this on Linux.
> All the documentation I found seems to indicate that the template dialog should respect the `Tools > Options > Date format` which I have set to `YYYY-MM-DD`, but it doesn't.
>
> (Is this a UI bug?)
>
> In the template I have:
>
> ```
> ---
> start_date: date
> end_date: date
> ```
>
>
>
> I have tried to set `LC_TIME` and to change the date format and language of the interface but neither seem to have an effect.
>
> I also tried to replace `start_date: date` with other variants, including `custom_datetime` but none were supported types.
>
> Is there any other way to ensure the template shows a date format consistent with the settings?

_Originally posted by @unode in [#87](https://github.com/joplin/plugin-templates/issues/87#issuecomment-3371494848)_