Describe the bug

The calendar SVG in the <b-form-datepicker> is wrapped by a button element, this button element needs to have a ARIA attribute. This currently fails accessibility requirements from multiple sources (Lighthouse, SiteImprove, etc.)

Steps to reproduce the bug

1. View page with <b-form-datepicker> element in Chrome
2. Run Lighthouse against that page
3. View accessibility results
4. See the error Buttons do not have an accessible name

Expected behavior

The button needs to have an ARIA label attached to it instead of just the SVG inside of the button to be compliant

Versions

Libraries:

• BootstrapVue: 2.5.0
• Bootstrap: 4.#.#
• Vue: 2.#.#

Environment:

• Device: Any
• OS: Any
• Browser: Chrome
• Version: Any

Demo link

This is visible on the documentation page for this element on the Bootstrap Vue site: https://bootstrap-vue.org/docs/components/form-datepicker

Additional context

Add any other context about the bug here.