Add ConfigurationProperty.toString() for debugging

Update `ConfigurationProperty` with a sensible `toString()` to help
debug task failures.

Author: philwebb

buildSrc/src/main/java/org/springframework/boot/build/context/properties/ConfigurationProperty.java

@@ -65,4 +65,9 @@ public boolean isDeprecated() {
 		return this.deprecated;
 	}
 
+	@Override
+	public String toString() {
+		return "ConfigurationProperty [name=" + this.name + ", type=" + this.type + "]";
+	}
+
 }