Fix SamlMetadataCreator runtime dependencies

Update SamlMetadataCreator to use runtime_deps and depend on the already
built saml__plugin target instead of compiling the plugin sources again.
The tool only needs these dependencies at runtime, not at compile time.

Also add the required runtime dependencies for the utility: Gerrit
server, args4j, jgit, bcprov and dropwizard-core.

A considered alternative was to use //plugins:plugin-lib instead of
listing the individual dependencies explicitly. However, that would add
unused dependencies and substantially increase the final artifact size.

Change-Id: I564e798bb90c1e4afc0ff2b7528ed32cf87c1340

BUILD

diff --git a/BUILD b/BUILD
index 8e19948..05555f0 100644
--- a/BUILD
+++ b/BUILD
@@ -31,12 +31,14 @@
 
 java_binary(
     name = "SamlMetadataCreator",
-    srcs = glob([
-        "src/main/java/com/googlesource/gerrit/plugins/saml/**/*.java",
-    ]),
     main_class = "com.googlesource.gerrit.plugins.saml.pgm.SamlMetadataCreator",
-    deps = SAML_DEPS + [
-        "//plugins:plugin-lib-neverlink",
+    runtime_deps = SAML_DEPS + [
+        ":saml__plugin",
+        "//java/com/google/gerrit/server",
+        "//lib:args4j",
+        "//lib:jgit",
+        "//lib/bouncycastle:bcprov",
+        "//lib/dropwizard:dropwizard-core",
     ],
 )