Allow configuration of libxml options for decoding XML

[veewee]

Q	A
Type	feature
BC Break	no
Fixed issues

Summary

Fixes phpro/soap-client#598

This allows for configuring the LIBXML_* options for decoding XML requests from the EncoderRegistry.

EngineOptions::defaults($wsdl)
    ->withEncoderRegistry(
        EncoderRegistry::default()
            ->setDecoderLibXmlOptions(LIBXML_PARSEHUGE)
    )

[rajivraman-MRM]

I've tested this against our failing code and it works! No longer errors with: [FATAL] : Resource limit exceeded: Text node too long, try XML_PARSE_HUGE. Tested against version 4.5.

I made this change to the generated client-factory in order to use it:

        $engine = DefaultEngineFactory::create(
            EngineOptions::defaults($wsdl)
                ->withEncoderRegistry(
                    EncoderRegistry::default()
                        ->setDecoderLibXmlOptions(LIBXML_PARSEHUGE) // NEW
                        ->addClassMapCollection(AdminClassmap::types())
                        ->addBackedEnumClassMapCollection(AdminClassmap::enums())
                )
...