Revamp support for building third-party apps via maven

- Publish onos-dependencies (autogenerated from deps.json). With most
  3rd-party dependencies listed as <dependencyManagement> to avoid
  version conflicts, and a minimal set listed as <dependencies> to
  simplify child poms. Similarly, we provide a number of plugins already
  configured as <pluginManagement> to support the whole life-cycle of
  apps (from build, to reporting and release).
- Update Maven plugins to work with JDK 11 (checkstyle, pmd, etc.)
- Publish onos-build-conf (with common checkstyle and pmd confs)
- Removed unused checkstyle code
- Fix OSGi version mismatch in deps.json to consistently depend on
  release 6 (the one supported by Karaf 4)
- Update/simplify archetypes to use onos-dependencies as the parent pom

Change-Id: Ic09b34e13fb49eb3d96df623b53a3617bbf7b7e4
diff --git a/tools/build/conf/BUILD b/tools/build/conf/BUILD
index 1eb4fae..bf1effb 100644
--- a/tools/build/conf/BUILD
+++ b/tools/build/conf/BUILD
@@ -1,3 +1,5 @@
+load("//tools/build/bazel:pom_file.bzl", "pom_file")
+
 checkstyle_source = "src/main/resources/onos/checkstyle.xml"
 
 suppression_source = "src/main/resources/onos/suppressions.xml"
@@ -27,3 +29,9 @@
     resources = glob(["src/main/resources/onos/**"]),
     visibility = ["//visibility:public"],
 )
+
+pom_file(
+    name = "onos-build-conf-pom",
+    artifact = "onos-build-conf",
+    visibility = ["//visibility:public"],
+)