Implement "Safe Delete" refactoring for classes and objects

idea/testData/safeDelete/deleteObject/nestedObject1.kt

@@ -0,0 +1,11 @@
+package test
+
+object A {
+    object <caret>O {
+
+    }
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/nestedObject1.kt.after

@@ -0,0 +1,8 @@
+package test
+
+object A {
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/nestedObject2.kt

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+package test
+
+import test.A.O
+
+object A {
+    object <caret>O {
+
+    }
+}
+
+class B {
+    val x = A.O
+}

idea/testData/safeDelete/deleteObject/nestedObject2.kt.messages

@@ -0,0 +1,2 @@
+Object O has 1 usage that is not safe to delete.
+Of those 0 usages are in strings, comments, or non-code files.

idea/testData/safeDelete/deleteObject/noUsages.kt

@@ -0,0 +1,11 @@
+class C {
+
+}
+
+object <caret>A {
+
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/noUsages.kt.after

@@ -0,0 +1,7 @@
+class C {
+
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/object1.kt

@@ -0,0 +1,11 @@
+package test
+
+import test.A
+
+object <caret>A {
+
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/object1.kt.after

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+package test
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/object2.kt

@@ -0,0 +1,11 @@
+package test
+
+import test.A
+
+object <caret>A {
+
+}
+
+class B {
+    val x = A
+}

idea/testData/safeDelete/deleteObject/object2.kt.messages

@@ -0,0 +1,2 @@
+Object A has 1 usage that is not safe to delete.
+Of those 0 usages are in strings, comments, or non-code files.

idea/testData/safeDelete/deleteObject/unsafeImport.kt

@@ -0,0 +1,11 @@
+package test
+
+import test.A.x
+
+object <caret>A {
+    val x = ""
+}
+
+class B {
+
+}

idea/testData/safeDelete/deleteObject/unsafeImport.kt.messages

@@ -0,0 +1,2 @@
+Object A has 1 usage that is not safe to delete.
+Of those 0 usages are in strings, comments, or non-code files.