Manage Extension page in the UI

Background

The reference application has a "Manage Apps" page, that you can see at http://demo.openmrs.org/openmrs/referenceapplication/manageApps.page. This page allows you to turn off and on the built-in app definitions, and also add your own new ones. We should have an equivalent page for managing Extensions.

The high-priority functionality is to be able to disable and enable the built-in app definitions. (There is a workaround for defining your own extensions via the Manage Apps page, so the Manage Extensions page won't need that feature in the first pass.)

See https://talk.openmrs.org/t/edit-the-vitals-form-in-reference-application/3293/4 for the original request for this.

Dev Notes

In this ticket you should basically copy-paste-edit the Manage Apps page, in order to manage Extensions. (Where the current page calls AppFrameworkService methods about Apps, you'd want to call the equivalent methods about Extensions.)

The Manage Apps page lives in openmrs-module-referenceapplication. See:

• https://github.com/openmrs/openmrs-module-referenceapplication/blob/master/omod/src/main/webapp/pages/manageApps.gsp
• https://github.com/openmrs/openmrs-module-referenceapplication/blob/master/omod/src/main/java/org/openmrs/module/referenceapplication/page/controller/ManageAppsPageController.java
• there are also js and scss files

This is a relatively large "intro" ticket, but it should be straightforward since it's nearly identical to existing code.

Extra Credit

You do not need to replicate the Add App page, but it would be a nice-to-have to do this. It would require doing some work in the App Framework module (equivalent to what was done in AF-44).