Fix dependencies for server-side deploy script (PR #10604)
The server side deploy code ('nvdaAppveyorHook') relies on artifacts, they must be uploaded before the deploy code is run.
The deploy_script phase is run before on_finish phase, so the artifacts were missing.
Instead, use the artifacts section, and also upload from on_failure.
For ordering of appveyor yml phases, see: https://www.appveyor.com/docs/build-configuration/#build-pipeline
Extended messages
A message containing the built exe link:
We know that the executable is present, since the name comes from the
'output' directory of the build. Though this depends on the artifact
uploading being successful.
Other build failure messages:
- Unable to install NVDA
- Unit test failure
- System test failure
