XWIKI-12148: Allow upgrading a flavor in Distribution Wizard

...ion/distribution/internal/job/DefaultDistributionJob.java

...istribution/internal/job/step/FlavorDistributionStep.java

...wiki/extension/script/AbstractExtensionScriptService.java

...xwiki/extension/script/ExtensionHistoryScriptService.java

...xwiki/extension/script/ExtensionManagerScriptService.java

...rc/main/java/org/xwiki/platform/flavor/FlavorManager.java

.../xwiki/platform/flavor/internal/DefaultFlavorManager.java

...ki/platform/flavor/script/FlavorManagerScriptService.java

...ldcore/src/main/resources/ApplicationResources.properties

.../main/webapp/templates/distribution/extension.flavor.wiki

...xwiki-platform-web/src/main/webapp/templates/extension.vm