Support of static functions with varargs

Expression Language API allows one to use a [FunctionMapper ](https://jakarta.ee/specifications/platform/10/apidocs/jakarta/el/functionmapper) to register a static function mapped to a [Method](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/reflect/Method.html). For example, `${str:format(...)}` could be mapped to [String.format()](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html#format(java.lang.String,java.lang.Object...)) function.

However, this does not work for methods with varargs. Thus, evaluation of `${str:format('%s%s', 'a', 'b')}` fails with:

```
jakarta.el.ELException: Function 'str:format' specifies 2 params, but 3 were supplied

at org.glassfish.expressly.lang.ExpressionBuilder.visit(ExpressionBuilder.java:244)
at org.glassfish.expressly.parser.SimpleNode.accept(SimpleNode.java:157)
at org.glassfish.expressly.lang.ExpressionBuilder.prepare(ExpressionBuilder.java:195)
at org.glassfish.expressly.lang.ExpressionBuilder.build(ExpressionBuilder.java:206)
at org.glassfish.expressly.lang.ExpressionBuilder.createValueExpression(ExpressionBuilder.java:255)
at org.glassfish.expressly.ExpressionFactoryImpl.createValueExpression(ExpressionFactoryImpl.java:95)
```

By contrast, varargs methods are supported for Java Beans. If "str" was registered as a [String ](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html) bean, then the following expression would work (note the '.' instead of the ':'): `${str.format('%s%s', 'a', 'b')}`.

There are two issues in expressly code:

1. `org.glassfish.expressly.parser.AstFunction.getValue()` contains a loop that coerces function arguments to the proper method parameter data types. This loop does not handle varargs. Instead, you may consider using `jakarta.el.ELUtil.buildParameters()` which does support varargs.
2. `org.glassfish.expressly.lang.ExpressionBuilder.visit()` compares the number of provided function arguments to the number of parameters of the method implementing this function. This logic does not consider variable number of arguments for varargs methods.