feat: action cancellation

[de-sh]

Closes #

Changes

Action mid execution should be cancellable at one of two places:

1. During execution in a preemptable stage, e.g. while downloading a file(should also delete file created as a result of partial download)
2. At the end of a non-preemptable stage, e.g. at the end of a system-update, but before a restart sequence that would apply the update, this allows the customer to tunshell into the device and make any revertions necessary, but this is just an example and needs more thinking.

As an example of how this can be configured at the application level, downloader is the first built-in to support cancellation, as part of the cancellation procedure, it will also delete a partially downloaded file.

Why?

Trials Performed

Awaiting backend support for testing