ignore unused params in main methods (IDEA-69989)

java/java-tests/testData/inspection/unusedMethodParameter/appMainUnusedParams/expected.xml

@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems></problems>
+

java/java-tests/testData/inspection/unusedMethodParameter/appMainUnusedParams/src/Test.java

@@ -0,0 +1,4 @@
+public class Test {
+  public static void main(String[] args) {
+  }
+}