Fix code generation for RequestType annotated lists

[JanTie]

Problem

Using a @RequestType annotation on List/Array parameters was not supported properly as the generated code treat the parameter builder as iterable, no matter what the type was actually mapped to. So for example the following code would previously cause ksp to generate non-compiling code:

interface MyDataSource {
    @GET
    suspend fun getData(
        @Url url: String,
        @Query("someFilterData") @RequestType(String::class) someFilterData: List<Filters>
    ): MyResponse
}

In this case the backend is supposed to work with a comma separated and html-encoded value for someFilterData. A converter factory should take care of that.

However, currently the generated code produces the following line

someFilterData?.filterNotNull()?.forEach { parameter("someFilterData", "$it") }

which does not compile, as the parameter is already expected to be a String at this point.

Change

The proposed change now no longer relies on the initial datatype to determine how the parameters are added to the request. Instead the actual mapped type causes the code generation to decide which approach is the correct one.

Also added an Example implementation of the stated ConverterFactory to the demo project