[TestSuite] Testing SDK function submission

Test the following scenarios in the function submission context:

- [x] Submit a non-existent function
- [x] Submit fn to a non-existent endpoint
- [ ] Submit fn to an endpoint not owned by the user
- [ ] Submit fn to an offline endpoint (we don't report endpoint status at this point. function will be 'pending' and no further info is expected at this time)
- [ ] Submit functions rapidly, to trigger throttling on the web-service side.