Update role-has-required-aria-props to support config to treat SHOULD props as required

[jessebeach]

For instance, aria-selected is recommended as a prop for the tab role, but it has a default value and it isn't marked as required. The following two lines are functionally equivalent.

<div role="tab" />
<div role="tab" aria-selected="false" />

With configuration, we can allow authors to require an explicit definintion of a prop like aria-selected on a role tab.

[ljharb]

This OP reads a bit like a two-person conversation coming from one person - can you clarify?