Kotlin Multiplatform Support

[idan-fido]

In order to make the client work with kmm projects
Need to rework the following:

1. replace usage of GSON with kotlin.serialization
2. replace use of android Context, Handler from FlagsmithAnalytics.kt with kotlin coroutines api
3. replace SharedPreferences in FlagsmithAnalytics.kt with multiplatform-settings
4. seems that Fuel (net lib) support kmm, but haven't tested, can consider replacing it with Ktor

Made a POC with ktor and kotlin.serialization
have not implement Analytics support yet

https://github.com/idan-fido/flagsmith-kotlin-multiplatform

gz#199