lambda completion: strip unnecessary parenthesis, generate parameter names as for override/implement (IDEA-121947)

(cherry picked from commit 273ae0329f28a5bec42847a8739faf8a815cab37)

java/java-tests/testData/codeInsight/completion/smartType/InLambdaPositionNameSubstitution-out.java

@@ -0,0 +1,9 @@
+interface I<T> {
+  void m(T t);
+}
+
+class Test {
+  public static void main(String[] args) {
+    I<String> i = s -> <caret>
+  }
+}

java/java-tests/testData/codeInsight/completion/smartType/InLambdaPositionNameSubstitution.java

@@ -0,0 +1,9 @@
+interface I<T> {
+  void m(T t);
+}
+
+class Test {
+  public static void main(String[] args) {
+    I<String> i = <caret>
+  }
+}

java/java-tests/testData/codeInsight/completion/smartType/InLambdaPositionSingleParam-out.java

@@ -0,0 +1,9 @@
+interface I {
+  void m(int x);
+}
+
+class Test {
+  public static void main(String[] args) {
+    I i = x -> <caret>
+  }
+}

java/java-tests/testData/codeInsight/completion/smartType/InLambdaPositionSingleParam.java

@@ -0,0 +1,9 @@
+interface I {
+  void m(int x);
+}
+
+class Test {
+  public static void main(String[] args) {
+    I i = <caret>
+  }
+}