Allow usage of different JMS brokers

BPMSPL-744 brought a dependency on ActiveMQ Artemis JMS client to the Workbench [1].
However this implementation can be used just ActiveMQ Artemis JMS aligned with client version used in RHDM war file. This strongly limits its usage. For example in OpenShift there is an jboss-amq-62 image, which cannot be used as JMS broker for RHDM due to JMS client incompatibility with this broker.
I think that better implementation would be to use Initial context to retrieve a connection factory available in the application server. This way the RHDM will become independent on JMS client.

[1] https://github.com/kiegroup/appformer/commit/93e21c3a2c3bd1eaacb6a5591fd5e71bcd37be63#diff-600376dffeb79835ede4a0b285078036R955