## Type of Change
- [x] New feature  

## Description
Add option to force kernel setting and tests for CLI `kernel set`.
Related to #575.

## Motivation and Context
This PR adds additional tests to ensure that we can set kernels from
local files, remote tar files, and local tar files. A new option `force`
is added to the `kernel set` subcommand which will overwrite an existing
kernel with the same name if one exists to make testing easier. The
tests ensure that a container can be started with the newly set kernel
and resets to the default recommended kernel when complete.

## Testing
- [x] Tested locally
- [x] Added/updated tests

Signed-off-by: Kathryn Baldauf <k_baldauf@apple.com>