Refactor extract separate modules for each platform from ebean-api dbplatform

platforms/all/src/main/java/io/ebean/platform/all/Assembly.java

@@ -0,0 +1,7 @@
+package io.ebean.platform.all;
+
+/**
+ * Nothing interesting here - look at ebean-api.
+ */
+public class Assembly {
+}

platforms/all/src/main/java/io/ebean/platform/all/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Composite dependency of all platforms.
+ */
+package io.ebean.platform.all;