Fix build signing (#1577)

* Invoke gradle task prepare to generate source, javadoc, pom.jar

* Enable explicit signing

Author: heyams

.pipelines/pipeline.user.windows.yml

@@ -14,6 +14,8 @@ versioning:
       command: '.scripts/version.cmd'
 signing_options:
   profile: '170'
+  files_to_sign: 'applicationinsights-agent-*.jar'
+  search_root: '**/agent/agent/build/libs'
 static_analysis_options:
   policheck_options:
     disable_tool_scan: false