g0-merge LagrangeFix not working (Note: feature may be deprecated)

[JunoRavin]

Regression tests rt-vm-init.lua and rt-vm-init-p2.lua have an issue with the Lagrange Fix, seemingly due to the driftSpeed being a vector function in higher than 1V. When running the following error is produced:
ProjectOnBasis: this updater was created for a scalar/vector field, not a vector/scalar field.

This issue is to document the problem, but we may be deprecating the LagrangeFix updater owing to it not always being useful because of how it changes the tails of the distribution to fix the energy. If iterative schemes for conservative BGK work, issue may be closed as we will be able to officially deprecate LagrangeFix

[ammarhakim]

I do not want to maintain the Lagrange fix. We should remove the code and also remove the corresponding regression tests. We need to work towards a proper fix using iterative methods, as we discussed last week, perhaps with acceleration to improve convergence. This should be done in G0 and hooked into G2 App system.