[Painless] Casting Tests for Object and Number (#36804)

This adds more casting tests with the original type as Object and then Number. Covers the entire set of possible numeric cases for these two types.

Author: jdconrad

modules/lang-painless/src/test/java/org/elasticsearch/painless/CastTests.java renamed to modules/lang-painless/src/test/java/org/elasticsearch/painless/GeneralCastTests.java

@@ -20,7 +20,7 @@
 package org.elasticsearch.painless;
 
 /** Tests for explicit casts */
-public class CastTests extends ScriptTestCase {
+public class GeneralCastTests extends ScriptTestCase {
 
     /**
      * Unary operator with explicit cast