Drop support for moduleForAcceptance

[scalvert]

This PR prepares for the potential of deprecating the a11yAuditIf helper. This helper can be merged into a11yAudit by allowing it to accept another optional parameter: URL. This allows for two things:

1. The aforementioned deprecation of an extra, largely unnecessary API (simplification)
2. The removal of the getLocation function, which returns window.location and exists only to provide a stubbing mechanism for the getUrlParameter function. By adding an extra URL param to a11yAudit, we can simply test that function by passing in the required value, and provide the default as window.location.

⚠️ This change also includes a breaking change that removes support for older test infra versions (folks using the long deprecated moduleForAcceptance test system) by removing window.a11yAudit support.