Remove RICH CPU Dispatching and enhance general SIMD vectorisation support

Builds on LHCb!933 (merged)

This MR does a few things.

Firstly, I have removed the runtime CPU capabilities detection and dispatch code. Instead I simply rely on the build platform settings to determine the SIMD level. This is necessary to allow the use of SIMD (Vc) types more generally, rather than in very localised places.

I have also updated the ray tracing tool to use the enhanced SIMD aware methods from the mirror segment finder tool.