Fix double quotes in diagnostic messages

For diagnostics without any parameters, the given text is simply rendered as a
String, so no symbols should be escaped.

For diagnostics with parameters, the format in java.text.MessageFormat is used,
so one single quote is erased and two single quotes become one single quote in
the rendered text.

idea/testData/checker/SafeInvoke.kt

@@ -2,7 +2,7 @@ class Rule(val apply: () -> Unit)
 
 fun foo() {
     val rule: Rule? = Rule { }
-    rule?.<error descr="[UNSAFE_IMPLICIT_INVOKE_CALL] Reference has a nullable type (() -> Unit)?, use explicit ?.invoke() to make function-like call instead">apply</error>()
+    rule?.<error descr="[UNSAFE_IMPLICIT_INVOKE_CALL] Reference has a nullable type '(() -> Unit)?', use explicit '?.invoke()' to make a function-like call instead">apply</error>()
     val apply = rule?.apply
-    <error descr="[UNSAFE_IMPLICIT_INVOKE_CALL] Reference has a nullable type (() -> Unit)?, use explicit ?.invoke() to make function-like call instead">apply</error>()
-}
+    <error descr="[UNSAFE_IMPLICIT_INVOKE_CALL] Reference has a nullable type '(() -> Unit)?', use explicit '?.invoke()' to make a function-like call instead">apply</error>()
+}