Add method to insert parameters at particular indices

[algomaster99]

As addressed in the issue here, diffmin requires methods for inserting CtElements at particular indices in collections. One such collection is of parameters. This issue is a request for a method that would allow us to insert a parameter at a particular index.

Like #3885, the method can be called CtMethod.addCtParameterAt.

[slarse]

Again, thanks for the feature request, to keep better track of it all I'll incorporate it into #3884 :)