feat(gcds-date-input): add yyyy-mm-dd input format

[radmorecameron]

Summary

Adds a yyyy-mm-dd format for gcds-date. This is useful for data entry. closes #969

Test instructions

I've added specs and updated the storybook. You can test using the storybook or:

Using the following HTML:

        <gcds-date-input
          legend="Year Month Day Date input"
          name="ymd-date-input"
          format="yyyy-mm-dd"
          hint="Formatted: YYYY-MM-DD"
        ></gcds-date-input>

1. date input should appear in year month day order regardless of language.

This will have conflicts with #989 so that PR should be merged first

[daine]

@radmorecameron thanks for the PR! In this instance, the date input component already has an established design counterpart. When it was first created, the team invested significant effort into defining its component specifications through research and design work.

Introducing a new date format (like this one) would need to go through our requirements and specifications phase before we can proceed with implementation. Since PRs usually come toward the end of our workflow, it may take some time before we can revisit this. Thanks for understanding!