Support several postfix live templates on the same key

Need it for GO-4845 where same postfix sort template is expanded
differently depending on the type of the element it is invoked on.

java/java-tests/testData/codeInsight/template/postfix/templates/editable/sameKeyBoolean.java

@@ -0,0 +1,5 @@
+public class Foo {
+  void m(boolean x) {
+    x.sameKey<caret>
+  }
+}

java/java-tests/testData/codeInsight/template/postfix/templates/editable/sameKeyBoolean_after.java

@@ -0,0 +1,5 @@
+public class Foo {
+  void m(boolean x) {
+      Boolean.toString(x);
+  }
+}

java/java-tests/testData/codeInsight/template/postfix/templates/editable/sameKeyInteger.java

@@ -0,0 +1,5 @@
+public class Foo {
+  void m(int x) {
+    x.sameKey<caret>
+  }
+}

java/java-tests/testData/codeInsight/template/postfix/templates/editable/sameKeyInteger_after.java

@@ -0,0 +1,5 @@
+public class Foo {
+  void m(int x) {
+      Integer.toString(x);
+  }
+}