Add helix fit covariance matrix to HYBRID output

[tomalin]

PR description:

Thanks to this PR, the covariance matrix obtained from the HYBRID KF fit is now stored in the TTTrack object, and a couple of histograms "resOverSigma*z0"plotting z0 resolution divided by the uncertainty in the z0 taken from this matrix have been added to L1TrackNtuplePlot.C .

In addition, the TTTrack object has been slightly tidied up. This clean up preserves backwards compatibility, so it should still be possible to read old datasets, but a couple of changes are needed to L1 trigger code.

1. Since the TTTrack function stubPtConsistency() was renamed chi2BendRed() some years ago, and this PR deletes the obsolete name, I've made a PR Delete obsolete TTTrack::stubPtConsistency function cms-sw/cmssw#49565 to central CMSSW to change the few L1 trigger routines that have not changed to the new name.
2. This PR explicitely splits into two the 6 bit field intended for track quality MVAs for electrons and displaced tracks. Previously, one function returned the 6 bits together.
   IMPORTANT: When a PR is made to central CMSSW, any L1 trigger code that still uses the original 6 bit "MVAOther" type names will need modifying in the PR too, to instead use the two 3 bit fields.

PR validation:

No change in tracking performance.