Form feature

[chriskapp]

Users who have build an API with Fusio need sometimes a quick way to create a form for a specific API endpoint. I.e. a user has created an Todo endpoint and want a simple form where users can submit new Todos through a simple UI. For this we could add a new Form panel at the backend and a new Form app which renders those forms.

At the backend panel a user could create a new Form by chossing a name, selecting an operation (probably only POST operations) and define a JSON
form which describes how to the form looks. At the form app we can use this JSON to render the form. We can use i.e. https://github.com/eclipsesource/jsonforms to render those forms but we could also use other solutions since at the backend we basically only specify a JSON payload to describe the form.