Use FirModuleBasedSession with module info, use platform default imports

In this commit, FIR sessions made bound to a particular module

compiler/tests-common/tests/org/jetbrains/kotlin/fir/FirTestModuleInfo.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir
+
+import org.jetbrains.kotlin.analyzer.ModuleInfo
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.resolve.TargetPlatform
+import org.jetbrains.kotlin.resolve.jvm.platform.JvmPlatform
+
+class FirTestModuleInfo(
+    override val name: Name = Name.identifier("TestModule"),
+    private val dependencies: List<ModuleInfo> = emptyList(),
+    override val platform: TargetPlatform = JvmPlatform
+) : ModuleInfo {
+    override fun dependencies(): List<ModuleInfo> = dependencies
+}