Hoist and expose BaseKotlinCompile.incremental

[ting-yuan]

Previously, Kotlin2JsCompile.incremental is configured from propertiesProvider.incrementalJs.

Now, it is a seprate, configurable value. Incremental compilation is enabled only if

incremental and (incrementalJs or incrementalJsKlib)

are enabled.

https://youtrack.jetbrains.com/issue/KT-54986/KGP-API-to-toggle-incremental-compilation