[CustomScript] extension should allow for a script payload

Given that uploading dependencies to an added storage account may be unfeasible (or just too much overhead) when using CLI scripting, this extension should support the use case of inlining a shell script as part of an ARM template - something like the example below would go a very long way towards matching this competing feature and allowing for easy migration.

        "settings": {
          "inlineScript": "#!/bin/bash\nsudo apt-get -y update\nsudo apt-get install nginx"
        }

[ahmetb]

@rcarmo your template will probably fail with error:

Custom data in OSProfile must be in Base64 encoding and with a maximum length of 87380 characters.

[ahmetb]

@rcarmo I was wrong about my earlier statement saying customData does accept non-base64 strings as well. It only accepts base64 strings and the docs are correct.

If you care about readability in your ARM templates you can specify a myScript in "variables" or "parameters" section and in customData field you can use:

"customData": "[base64(variables('myScript'))]"

so it essentially is the same thing as if customData accepted non-base64 strings.