Remove all compile-time dependencies upon ShrinkWrap Descriptors Impl Module

Arquillian relies upon internals of ShrinkWrap Descriptors for compilation in:

arquillian-config
arquillian-protocol-servlet

Because the implementation of SD is subject to change over time, we must remove the compile dependency here by either moving bits to a stable SD SPI, and/or moving code temporarily to ARQ. This temporary code may be removed when the SD API becomes stable and back-compat guaranteed.