Add guardrail to displayable app params

[Bubballoo3]

If an app is configured incorrectly, a sensitive field like a password may have the display: true attribute, causing it to show up on popups introduced in #4515. If there are other places that displayable parameters show up, we may want to add this sensitivity check in the display? method itself, so that a display: true setting is overridden if there is an indication that the field is sensitive.

[Bubballoo3]

@johrstrom how do you recommend detecting the sensitivity of a particular attribute? It doesn't look like we have any other method for sensitive? or similar, so it is just hardcoding display? == false whenever the attribute name is 'password'?