Merge template rendering web ui bundle into web-ui

Move:

• https://github.com/nuxeo/nuxeo-template-rendering/tree/master/nuxeo-template-rendering-web-ui
• https://github.com/nuxeo/nuxeo-template-rendering/tree/master/nuxeo-template-rendering-jaxrs-web-ui

to https://github.com/nuxeo/nuxeo-web-ui.

Note this addon can be installed with nuxeo-template-rendering-samples which contains a
template-module-demo jar which has document layouts for web ui. Not sure where they are from. Studio? but I don't see them in https://connect.nuxeo.com/nuxeo/site/studio/ide?project=template-module-demo