Configurable headings

[WickyNilliams]

There should be some way to configure the various headings. Rather than month and year being separate, maybe you want a single heading that encompasses both

The easy option would be to expose some formatting options as props.

But i would prefer to lean into composition if possible with a <calendar-heading> component, which is itself configurable. It should be possible to place this anywhere as a descendant of the other components, and it Just Works