Added feature to "Convert to expression body" intention: selection for easier explicit type removal

idea/testData/intentions/convertToExpressionBody/anonymousObjectExpression.kt.after

@@ -2,7 +2,7 @@ trait I {
     fun foo(): String
 }
 
-fun bar(): I = object: I {
+fun bar()<selection>: I</selection> = object: I {
     override fun foo(): String {
         return "a"
     }

idea/testData/intentions/convertToExpressionBody/funWithImplicitUnitTypeWithThrow.kt.after

@@ -1,3 +1,3 @@
 // WITH_RUNTIME
 
-fun foo(): Unit = throw UnsupportedOperationException()
+fun foo()<selection>: Unit</selection> = throw UnsupportedOperationException()

idea/testData/intentions/convertToExpressionBody/funWithNothingType.kt.after

@@ -1,3 +1,3 @@
 // WITH_RUNTIME
 
-fun foo(): Nothing = throw UnsupportedOperationException()
+fun foo()<selection>: Nothing</selection> = throw UnsupportedOperationException()

idea/testData/intentions/convertToExpressionBody/funWithReturn.kt.after

@@ -1 +1 @@
-fun foo(): String = "abc"
+fun foo()<selection>: String</selection> = "abc"

idea/testData/intentions/convertToExpressionBody/funWithUnitTypeWithThrow.kt.after

@@ -1,3 +1,3 @@
 // WITH_RUNTIME
 
-fun foo(): Unit = throw UnsupportedOperationException()
+fun foo()<selection>: Unit</selection> = throw UnsupportedOperationException()

idea/testData/intentions/convertToExpressionBody/protectedFunNoSelection.kt

@@ -0,0 +1,5 @@
+open class A {
+    protected fun <caret>foo(): String {
+        return "abc"
+    }
+}

idea/testData/intentions/convertToExpressionBody/protectedFunNoSelection.kt.after

@@ -0,0 +1,3 @@
+open class A {
+    protected fun <caret>foo(): String = "abc"
+}

idea/testData/intentions/convertToExpressionBody/publicFunNoSelection.kt

@@ -0,0 +1,3 @@
+public fun <caret>foo(): String {
+    return "abc"
+}

idea/testData/intentions/convertToExpressionBody/publicFunNoSelection.kt.after

@@ -0,0 +1 @@
+public fun <caret>foo(): String = "abc"