Package lambda and upload directly to S3

Create a one-step ZIP creation instead of the following:

```bash
#!/bin/sh

NAME=...

xp lambda package src vendor config.ini
aws s3 cp function.zip s3://timms-xp-deployment/lambdas/$NAME.zip
```

Idea: `xp lambda upload s3://timms-xp-deployment/lambdas/$NAME.zip [...]`