Add "Control flow with empty body" inspection

#KT-30970 Fixed

idea/testData/inspectionsLocal/controlFlowWithEmptyBody/ifElse/block.kt

@@ -0,0 +1,8 @@
+// PROBLEM: 'else' has empty body
+// FIX: none
+
+fun test(i: Int) {
+    if (i == 1) {
+    } <caret>else {
+    }
+}

idea/testData/inspectionsLocal/controlFlowWithEmptyBody/ifElse/blockHasComment.kt

@@ -0,0 +1,9 @@
+// PROBLEM: 'else' has empty body
+// FIX: none
+
+fun test(i: Int) {
+    if (i == 1) {
+    } <caret>else {
+        // comment
+    }
+}

idea/testData/inspectionsLocal/controlFlowWithEmptyBody/ifElse/blockHasStatement.kt

@@ -0,0 +1,10 @@
+// PROBLEM: none
+
+fun test(i: Int) {
+    if (i == 1) {
+    } <caret>else {
+        foo()
+    }
+}
+
+fun foo() {}

idea/testData/inspectionsLocal/controlFlowWithEmptyBody/ifElse/single.kt

@@ -0,0 +1,6 @@
+// PROBLEM: 'else' has empty body
+// FIX: none
+
+fun test(i: Int) {
+    if (i == 1) {}<caret>else {};
+}

idea/testData/inspectionsLocal/controlFlowWithEmptyBody/ifElse/singleHasStatement.kt

@@ -0,0 +1,8 @@
+// PROBLEM: none
+
+fun test(i: Int) {
+    if (i == 1) {
+    } <caret>else foo()
+}
+
+fun foo() {}