SE: add symbolic engine support for Boolean constraints

[costin-zaharia-sonarsource]

The engine should automatically add True or False constraints for symbols and operations which can be evaluated as True or False. E.g.:

• literals: true and false like in new Mutex(true)
• simple equality checks: 1 == 1

[pavel-mikula-sonarsource]

The 1 == 1 should work by checking every operation to see if .ConstantValue is true/false. It should also work for cases like

const int zero = 0;
var b = zero == 0;