Summary:
DataDescriptor currently shows a pencil icon next to text values starting with http/https. This is because otherwise it wouldn't be possible to edit them as a click would open the link in a web browser instead of triggering the edit mode.
Because of how this logic is implemented, it doesn't take into account whether editmode is enabled or not, thus it shows the pencil icon even when there's no need for it (custom plugins with no edit mode).
## Changelog
Fixed pencil icon visible in DataInspector for non-editable text fields
Pull Request resolved: https://github.com/facebook/flipper/pull/1002
Test Plan:
I tested this locally with LayoutInspector and my own custom plugin. The pencil still appears and works in the LayoutInspector but doesn't show up anymore in my custom plugin as the data there is not editable
## Result after the fix:
**Editable (LayoutInspector)**

**Non-Editable (Custom Plugin)**

Reviewed By: passy
Differential Revision: D21400359
Pulled By: mweststrate
fbshipit-source-id: 62b18f3f6c75c1b07440d51fca363d7e6fc60c6a