Add tempfile module

[s-hamann]

I implemented the tempfile module.
It works mostly like Ansible's reference implementation with the exception of the suffix parameter. This parameter is ignored here, because BusyBox mktemp does not support a suffix.
As a workaround, I considered renaming the file/directory to add the suffix, but found that to be difficult to check without creating a race condition.

[Jonny007-MKD]

did you consider writing a test? From the readme:

Writing tests for your new module is also highly recommended.

[s-hamann]

Yes, tests would make sense. I'll see if I can find the time.