Mark Formatter as provided, remove dependency on Arc.

Change-Id: Ia5faeefbaf541381e44c53f621d0c08ae28ec2ad
diff --git a/runtime/pom.xml b/runtime/pom.xml
index 8b6616b..f0f502a 100644
--- a/runtime/pom.xml
+++ b/runtime/pom.xml
@@ -15,7 +15,7 @@
   <dependencies>
     <dependency>
       <groupId>io.quarkus</groupId>
-      <artifactId>quarkus-arc</artifactId>
+      <artifactId>quarkus-core</artifactId>
     </dependency>
     <dependency>
       <groupId>io.quarkus</groupId>
diff --git a/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
index d6eeb0e..0c691b7 100644
--- a/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
+++ b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
@@ -17,7 +17,7 @@
  *
  * @see LogEntry
  */
-class Formatter extends ExtFormatter {
+public class Formatter extends ExtFormatter {
 
   private static final String TRACE_LEVEL = "TRACE";
   private static final String DEBUG_LEVEL = "DEBUG";
diff --git a/runtime/src/main/java/module-info.java b/runtime/src/main/java/module-info.java
index 56b44fc..a78ae6e 100644
--- a/runtime/src/main/java/module-info.java
+++ b/runtime/src/main/java/module-info.java
@@ -1,3 +1,5 @@
+import eu.mulk.quarkus.googlecloud.jsonlogging.Formatter;
+
 module quarkus.googlecloud.jsonlogging {
   requires java.logging;
   requires java.json;
@@ -6,4 +8,9 @@
   requires smallrye.common.constraint;
 
   exports eu.mulk.quarkus.googlecloud.jsonlogging;
+
+  provides java.util.logging.Formatter with
+      Formatter;
+  provides org.jboss.logmanager.ExtFormatter with
+      Formatter;
 }