HttpProxy cannot set setURLStreamHandlerFactory when Prospero is used under a modular environment.

[yersan]

When Prospero runs in a modular environment HttpProxy will generate always a warning since JBoss Modules already configures the URL.setURLStreamHandlerFactory

This is shown for example when Prospero is used under the server integration, where the update command generates the following warning:

17:36:45,715 WARN  [org.wildfly.channel.proxy.HttpProxy] (management-handler-thread - 1) Unable to URL.setURLStreamHandlerFactory: java.lang.Error: factory already defined
	at java.base/java.net.URL.setURLStreamHandlerFactory(URL.java:1232)
	at org.jboss.prospero//org.wildfly.channel.proxy.HttpProxy.setup(HttpProxy.java:74)
	at org.jboss.prospero//org.wildfly.channel.ChannelMapper.<clinit>(ChannelMapper.java:69)
	at org.jboss.prospero//org.wildfly.prospero.model.ProsperoConfig.readConfig(ProsperoConfig.java:77)
	at org.jboss.prospero//org.wildfly.prospero.api.InstallationMetadata.loadInstallation(InstallationMetadata.java:93)
	at org.jboss.prospero//org.wildfly.prospero.actions.UpdateAction.<init>(UpdateAction.java:57)
	at org.jboss.prospero//org.wildfly.prospero.spi.ProsperoInstallationManager$ActionFactory.getUpdateAction(ProsperoInstallationManager.java:321)
	at org.jboss.prospero//org.wildfly.prospero.spi.ProsperoInstallationManager.findUpdates(ProsperoInstallationManager.java:120)
	at [email protected]//org.wildfly.core.instmgr.InstMgrListUpdatesHandler$1.execute(InstMgrListUpdatesHandler.java:134)
	at [email protected]//org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:1065)
	at [email protected]//org.jboss.as.controller.AbstractOperationContext.processStages(AbstractOperationContext.java:786)
	at [email protected]//org.jboss.as.controller.AbstractOperationContext.executeOperation(AbstractOperationContext.java:477)
	at [email protected]//org.jboss.as.controller.OperationContextImpl.executeOperation(OperationContextImpl.java:1450)
	at [email protected]//org.jboss.as.controller.ModelControllerImpl.internalExecute(ModelControllerImpl.java:449)
	at [email protected]//org.jboss.as.controller.ModelControllerImpl.lambda$executeForResponse$0(ModelControllerImpl.java:259)
	at [email protected]//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:304)
	at [email protected]//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:270)
	at [email protected]//org.jboss.as.controller.ModelControllerImpl.executeForResponse(ModelControllerImpl.java:259)
	at [email protected]//org.jboss.as.controller.ModelControllerImpl.executeOperation(ModelControllerImpl.java:253)
	at [email protected]//org.jboss.as.controller.ModelControllerImpl.execute(ModelControllerImpl.java:236)
	at [email protected]//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler.doExecute(ModelControllerClientOperationHandler.java:239)
	at [email protected]//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:161)
	at [email protected]//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1$1.run(ModelControllerClientOperationHandler.java:157)
	at [email protected]//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:328)
	at [email protected]//org.wildfly.security.auth.server.SecurityIdentity.runAs(SecurityIdentity.java:285)
	at [email protected]//org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:254)
	at [email protected]//org.jboss.as.controller.AccessAuditContext.doAs(AccessAuditContext.java:225)
	at [email protected]//org.jboss.as.controller.remote.ModelControllerClientOperationHandler$ExecuteRequestHandler$1.execute(ModelControllerClientOperationHandler.java:157)
	at [email protected]//org.jboss.as.protocol.mgmt.ManagementRequestContextImpl$1.doExecute(ManagementRequestContextImpl.java:70)
	at [email protected]//org.jboss.as.protocol.mgmt.ManagementRequestContextImpl$AsyncTaskRunner.run(ManagementRequestContextImpl.java:160)
	at [email protected]//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
	at [email protected]//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
	at [email protected]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
	at [email protected]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
	at java.base/java.lang.Thread.run(Thread.java:834)
	at [email protected]//org.jboss.threads.JBossThread.run(JBossThread.java:513)

This issue could be affecting the behaviour added by #208