Use CACCS for affine systems with constant vectors

[schillic]

Instead of artificially wrapping constant vectors of affine systems as inputs with Singleton domain, Reachability supports CACCS.
Modeling constant vectors this way should be equivalent, but we should compare the results just to be sure.

The corresponding models are:

• MNA1/MNA5
  

  ReachabilityBenchmarks/models/SLICOT/mna1/mna1.jl

  Line 21 in d7093d6

  U = Hyperrectangle([fill(0.1, 5); fill(0.2, 4)], zeros(9))

• filtered oscillator
  

  ReachabilityBenchmarks/models/SpaceEx/FilteredOscillator/FilteredOscillator.jl

  Line 37 in d7093d6

  U = Singleton([1.0])

• projectile
  

  ReachabilityBenchmarks/models/Custom/projectile/projectile.jl

  Line 16 in d7093d6

  U = Singleton([0.,0.,0.,-9.81])

• gearbox
  

  ReachabilityBenchmarks/models/ARCH/AFF/Gearbox/Gearbox.jl

  Line 48 in d7093d6

  U = Singleton([1.])

• spacecraft rendezvous
  

  ReachabilityBenchmarks/models/ARCH/AFF/Rendezvous/SpacecraftRendezvous.jl

  Lines 33 to 34 in ad00577

  	B = sparse([t], [1], [1.], n, 1)
  	U = Singleton([1.])

Special case where inputs and a constant vector are mixed:

• platooning (I decided to keep it as is for efficient set representation)
  

  ReachabilityBenchmarks/models/ARCH/AFF/Platooning/Platooning.jl

  Line 48 in d7093d6

  U = Hyperrectangle(low=[-9., 1.], high=[1., 1.]) # acceleration of the lead vehicle + time