1452163 - [scriptworker] Move scope handling to scriptworker

Status: NEW

(Release Engineering :: Release Automation, enhancement)

Description

[Tom Prince [:tomprince]]

In Bug 1421062, I added support for using different taskcluster scope prefixes to all the scriptworkers to support having different scopes for thunderbird

Each of the scriptworkers has almost identical functions `get_task_{server,action,bucket}`. There is no reason for these functions to be duplicated in each script.

Additionally, the configuration for the scope prefix includes the worker type. The in-tree code hard-codes the script-type in the scope, so the workers should do the same. (i.e. the specified scope prefix is `project:releng:` instead of `project:releng:<script-type>:`.