fix: require org.slf4j.binding.nop in test bundle to attach SLF4J binding

The p2 planner does not automatically include fragment bundles in the
test runtime unless explicitly required. org.slf4j.binding.nop is an
OSGi fragment of org.slf4j.api, so adding Require-Bundle causes Tycho
to include it, at which point the OSGi framework attaches it to the
org.slf4j.api 1.7.30 host bundle and provides StaticLoggerBinder.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: joaodinissf

com.avaloq.tools.ddk.xtext.test/META-INF/MANIFEST.MF

@@ -32,7 +32,8 @@ Require-Bundle: com.avaloq.tools.ddk.xtext,
  junit-vintage-engine,
  junit-platform-suite-api,
  org.eclipse.xtext.testing,
- org.opentest4j
+ org.opentest4j,
+ org.slf4j.binding.nop;resolution:=optional
 Import-Package: com.avaloq.tools.ddk.check.runtime.test.core,
  com.avaloq.tools.ddk.check.test.core,
  com.avaloq.tools.ddk.check.test.runtime.tests,