Optimize Imports tests: Switch to generated approach

Move test and rename test data
Delete unused testdata
Rewrite OptimizeImportOnFlyTest

idea/testData/editor/optimizeImports/KotlinPackage/KotlinPackage.after.kt

@@ -0,0 +1,3 @@
+import test1.test2
+
+val s: test2.test3.Class1? = null

idea/testData/editor/optimizeImports/KotlinPackage/KotlinPackage.kt

@@ -0,0 +1,6 @@
+import test1
+import test1.test2
+import test1.test2.test3
+import test1.test2.test3.Class1
+
+val s: test2.test3.Class1? = null

idea/testData/editor/optimizeImports/KotlinPackage/kotlinClass.kt

@@ -0,0 +1,4 @@
+package test1.test2.test3
+
+public class Class1 {
+}