Introduce NameType

[The-Ray-Man]

This PR updates how we specify the name type. Before there was a string property mangledType on SymbolicName. This property describes what kind of entity the name refers to e.g. getter, property, function, type.

This strings should be duplicate free but they are distributed in many files. To have a better overview on the used strings a sealed class NameType was introduced which collects all the name types.

The changes in the resulting viper program can be categorized into:

• type name update: Before the type of a function looked like this TF$T$Unit which was changed to t$F$t$Unit. Basically the upper case T was replaced with a lowercase to match the other type names. Also it was separated using $.
• Label names changed slightly. E.g. try_exit to tryExit
• Parameters in the type domain changed from arg1 to arg$1
• Property getters type name is just g instead of pg
• Predicates are prefixed with pred instead of p
• Parameters are prefixed with par instead of p

Note: The NameType Special will be removed in a future PR. It makes sense to remove it, once we got rid off the SpecialName. Removing SpecialName requires a larger reconstruction.