Add simple checker tests for scripts

idea/testData/checker/scripts/if.kts

@@ -0,0 +1,10 @@
+val c = true
+if (c) {
+    2 + 3
+}
+
+fun f() {
+    if (!c) {
+        3 + 4
+    }
+}

idea/testData/checker/scripts/packageStatement.kts

@@ -0,0 +1,3 @@
+package org.my
+
+val x = 1

idea/testData/checker/scripts/simple.kts

@@ -0,0 +1,26 @@
+fun f() {
+}
+
+fun g() {
+    f()
+}
+
+val c = 1
+
+1 + 2
+
+val k = f()
+
+3 + 5
+
+g()
+f()
+
+class C {
+    fun f() {
+    }
+}
+
+val cc = C()
+
+cc.f()

idea/testData/checker/scripts/uninitializedVariable.kts

@@ -0,0 +1,2 @@
+val x = <error descr="[UNINITIALIZED_VARIABLE] Variable 'y' must be initialized">y</error>
+val y = 3