Add value access implementation of the Provision interface
by direct cast and access to the embedded value in `ParamData<VAL>`;
obviously this is an indirect dispatch, based on the actual type `VAL`
The test demonstrates the basic machinery built thus far
- have an embedded container with inline storage
- dispatch using type information encoded into the VTable
- `Disposition` is the service-API used by the front-End container
- `ParamData<TY>` is a complete implementation with a inline-value buffer
- The front-End is based on the `PolymorphicValue` container from our support-Lib
While the role of all the relevant interfaces has been determined,
it still remains difficult to establish a sensible relationship.
Which one is the most fundamental interface?
After a lot of mulling, it seems that the `Provision` interface
should be used as foundation, since it describes the very core
of the parameter concept developed here -- even while the actual
form of the operations must be ''somewhat cunningly reversed'',
so that the knowledge regarding the underlying type can be
kept an opaque implementation detail.
The `Domain` interface would then be layered on top, and describes
the capability to transfer values between buffers marked with different
domains (which effectively requires a double-dispatch in the general case).
Parameters and Automation will certainly play a crucial role eventually.
They will form a network of relationships to cover all further concerns that can not directly be conceptualised as arrangement or processing.
A shift in the setup of the Job-Functor arguments necessitates to introduce a `Parameter` type — ''albeit just as placeholder''
