Add complementary Kotlin support

[vmutafov]

Currently, the way to use Kotlin features in a NativeScript app is by using them as used in a Java code e.g. https://kotlinlang.org/docs/reference/java-to-kotlin-interop.html

There should be a more convenient way of using some features in JS/TS code, thus I propose the following additions to NativeScript's Kotlin support:

• [x] Add support for calling Kotlin non-boolean properties as used in Kotlin itself
• [ ] Add support for calling Kotlin boolean properties as used in Kotlin itself
• [ ] Add support for requesting an instance of a Kotlin object without accessing the INSTANCE field
• [x] Add support for calling Kotlin extension functions/properties on a given type as used in Kotlin without using the generated static methods
• [ ] Add support for mapping JS/TS lambdas and functions to Kotlin's functional interfaces (https://github.com/JetBrains/kotlin/blob/master/spec-docs/function-types.md)
• [ ] Add support for calling Companion objects' method as used in Kotlin without needing them to be declared as @JvmStatic
• [ ] Add support for overriding Kotlin properties when extending a Kotlin class using the JS/TS property syntax instead of overriding the getProperty/setProperty methods
• [ ] Add support for calling Kotlin functions which accept an unsigned number as a parameter