Add initial flow parameter for ramping constraints

[datejada]

Add the constraints to handle the case k=1, then we will need a new parameter for the initial flow (k=0) in the input data, with default = 0, and then write the constraints in these places:

TulipaEnergyModel.jl/src/constraints/ramping-and-unit-commitment.jl

Line 175 in 95f4ad1

@constraint(model, 0 == 0) # Placeholder for case k = 1

TulipaEnergyModel.jl/src/constraints/ramping-and-unit-commitment.jl

Line 199 in 95f4ad1

@constraint(model, 0 == 0) # Placeholder for case k = 1

TulipaEnergyModel.jl/src/constraints/ramping-and-unit-commitment.jl

Line 230 in 95f4ad1

@constraint(model, 0 == 0) # Placeholder for case k = 1

TulipaEnergyModel.jl/src/constraints/ramping-and-unit-commitment.jl

Line 252 in 95f4ad1

@constraint(model, 0 == 0) # Placeholder for case k = 1