provide jflexToKotlin plugin for newer intellij versions

[Martmists-GH]

It seems the old plugin can't be compiled directly on current versions, and after minimal fixing up to target latest IntelliJ, it fails to convert the lexer. Using the standard Java-to-Kotlin converter also seems to not work reliably as it still uses a good amount of java-exclusive classes and methods.

[fishinthecalculator]

Is there any known workaround for this? At least are the Java classes supposed to be usable in a Kotlin Multiplatform project?

[ice1000]

Beware that the generated toLowercase needs to be changed to lowercase