Clean up T-track combiners and define standard builders

The aim of this MR is to clean up some of the existing T-track builders, and define standard builders to use across WGs.

Currently, the T-track combiners are defined in bandq, but these are being used across multiple WGs, with some MRs duplicating the code.

Given the complexities of selections with T tracks (extrapolation, large combinatorics, decreased resolution, etc), it makes sense to minimise the number of builders where possible.

There are currently two reconstruction sequences, depending on whether or not the T track combination can be "gated" by a rare process. If it can't, a two step MVA filtering is applied to the tracks before running the full reco sequence to improve throughput.

This would imply four builders:

• MVA filtered (should be default)
  • $\Lambda$
  • $K_S^0$
• Unfiltered (for "gated" control flows only)
  • $\Lambda$
  • $K_S^0$

To-do:

• Decide best location (decided to be standard_particles)
• Copy to standard_particles
• Clean up existing code