Support dark theme in gerkin ewditor

### 👓 What did you see?

When I use dark theme I see black text on black background

### ✅ What did you expect to see?
Use color from theme

### 📦 Which tool/library version are you using?

Cucumber Eclipse 2.0.0.202205250851 cucumber.eclipse.feature.feature.group null

Eclipse
Version: 2022-03 (4.23.0)
Build id: 20220310-1457
### 🔬 How could we reproduce it?
Set dark theme on Eclipse preferences
open Gerkin File

Steps to reproduce the behavior:
1. Install '...' version '...'
2. Create a file called '....'
3. Run command '....'
4. See error '....'

### 📚 Any additional context?

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