General renaming and syntax

[Qubitol]

Note: do this after CI is all green: indeed it depends on several hardcoded names, so changing one requires checking in the CI for the same name and change it there for good

Follow the development on the branch feat-big-renaming.

• Rename bin/mg5_aMC to bin/madgraph (or bin/madgraph7, or other name)
• Rename standalone_mg7 to standalone and current standalone to standalone_fortran
• Rename backends GPU and C++ + dl-open logic
• Rename default process names PROCMG7_ to PROC_
• Rename _quark, _anti_quark to Q, Qx in the diagrams, same for leptons
• Rename the 🚀 to the prompt name we will decide to use
• Rename madevent.py (since it is no longer called madevent7).
• Remove unused files from the mg7 template folder

[stloufra]

• rename caches for storing previous commands to differ between mg5 and mg7
  ~/.config/mg5_history -> ~/.config/mg7_history

[oliviermattelaer]

change default value for run_card

• pass in dynamical scale by default
• set lhef output by default
• reduced allow-overweight
• zip lhe file by default
• systematics on true
• default value for the lepton rapidity (different from madevent?)
• cppnone is currently the default -> cppauto ?
• move to newer NNPDF version