JVM IR: remove dependency of 'backend.jvm' on 'psi2ir', 'ir.serialization.jvm'

Add a new module 'backend.jvm.entrypoint' which depends on psi2ir and
contains code that runs psi2ir + JVM IR backend with serialization
implementations.

Hopefully this will allow to compile these modules in parallel and
reduce the build time.

build.gradle.kts

@@ -242,6 +242,7 @@ extra["compilerModules"] = arrayOf(
     ":compiler:ir.psi2ir",
     ":compiler:ir.backend.common",
     ":compiler:backend.jvm",
+    ":compiler:backend.jvm:backend.jvm.entrypoint",
     ":compiler:backend.js",
     ":compiler:backend.wasm",
     ":compiler:ir.serialization.common",