[#325] Remove useless error entities from `Michelson.Interpret`

Description

There are two ways to report typechecker error in the ExecutorError datatype from Michelson.Runtime:

• Use EEIllTyped* constructors of ExecutorError
• Use IllTyped* constructors of InterpretError from Michelson.Interpret

It can lead to difficulties in pattern-matching over errors, because double error handlings is basically needed for this.

However, we use these IllTyped* constructors only in interpretUntyped function, which is not used anywhere in the project.

The solution is to get rid of interpretUntyped and IllTyped* as a result. This doesn't influence other modules.

Related issue(s)

Resolves #325 (closed)

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