[JDG] Add support for compatibility mode

New to this release is support for Compatibility Mode in JDG caches. Compatibility Mode allows for protocol interoperability, wich can be described as allowing data in the form of raw bytes to be read/write using different protocols, such as REST, Memcached and Hot Rod, written in different languages, such as C++ or Java. By default, the support for Compatibility Mode is disabled for any configured cache. In order to enable it, two new environment variables were introduced: ${prefix}_CACHE_PROTOCOL_COMPATIBILITY     Optional, can be set for each configured cache. The ${prefix} corresponds to the name of the cache. This variable enables/disables compatibility mode. Default is disabled, the value "true" will enable it. ${prefix}_CACHE_COMPATIBILITY_MARSHALLER     Optional, can be set for each configured cache. The ${prefix} corresponds to the name of the cache. This variable configures the Marshaller for use in compatibility mode, and will be considered only if compatibility mode is enabled for the specified cache though the ${prefix}_CACHE_PROTOCOL_COMPATIBILITY environment variable, as described above. As of JDG 7.1, it does not support the configuration of external marshallers, only internal pre-existing ones (e.g. org.infinispan.commons.marshall.JavaSerializationMarshaller and org.infinispan.commons.marshall.jboss.GenericJBossMarshaller). Reference documentation: https://access.redhat.com/documentation/en-us/red_hat_jboss_data_grid/7.1/html-single/administration_and_configuration_guide/#protocol_interoperability