Do not rename SideCondition variables when applying equations

[ttuegel]

checkRequires renames the variables of the SideCondition before sending its query to the solver. Instead, we should rename the variables in the result before calling checkRequires: if the check passes, we will need the renamed equation anyway, and even if the check does not pass, the equation's result is almost always smaller than the SideCondition and faster to rename.

[ttuegel]

I am electing to postpone this after #1545.

[ttuegel]

This is already half-way done: The requires is already renamed. Next, we need to change every function in Kore.Equation.Application which takes a SideCondition (Target variable) argument to take a SideCondition variable argument instead. These functions are:

• attemptEquation
• checkRequires
• targetEquationVariables

For targetEquationVariables, it will probably be necessary to mark the variables NonTarget after they are extracted from the SideCondition, but that should be fast.