show area: [TAB] for field navigation only works in some fields

When editing fields in the Show area, one expected (standard) UI behaviour is that [TAB] allows navigation between the UI fields. Currently, this works for most fields except for:

• Untertitel & Beschreibung on Show Page
• Zusammenfassung & Inhalt on Episode Editor
• image upload block (when stepping through all fields in show area & episode editor with [TAB], the image uploader is not included)

Being able to consistently use TAB for navigation creates a faster workflow, thus improving UX and facilitating ease and speed for ProKos. Moreover, consistent keyboard navigation behaviour improves usability for visually impaired users.

The inconsistency was also reported during Show Area testing by Vera (FRO Proko).