Reference "applied role" in axs.utils.getRoles

[ricksbrown]

The ARIA spec allows for multiple roles but only one is applied.
axs.utils.getRoles should indicate which role was "applied" as this is likely to be required in many cases.

For example given the element below:

<span role="foo bar checkbox button">

axs.utils.getRoles should indicate that the applied role is checkbox.

This is best implemented as a new property applied on the return value which references the applied role roleObject.

[ricksbrown]

This was closed by PR#138