Clean up the parameter definitions

• Define consistently named enums, BoundParametersIndices, FreeParametersIndices, and SpacePointIndices, for the components of all parameter-like objects. This fixes #718 (closed).
• Define prefixed values for all enums to avoid name clashes in the future.
• Define eBoundParametersSize, eFreeParameterSize, and eSpacePointSize as consistent enum values for size and use them throughout the code base. Remove BoundParsDim, FreeParsDim, and SpacePointDim.
• Define consistently named typedefs, BoundParametersScalar, FreeParametersScalar, and SpacePointScalar, for the underlying scalar types of all parameter-like objects. At the moment they are all double's but this allows us to play around with them separately.
• Define the default parametrization directly in the header and only read the override when requested to via the ACTS_PARAMETER_DEFINITIONS_HEADER cmake option. This is one less file to read during the compilation and also serves as documentation what the override header is expected to contain.

Most previous names are still available as typedefs to the new ones to reduce the scope of this MR.