Currently, when `FileDownloader.downloadFile()` encounters an error
during `client.execute()` (e.g., XPC connection interruption or network
timeout), the `HTTPClient` instance is deallocated without calling
`shutdown()`, resulting in a crash:
`AsyncHTTPClient/HTTPClient.swift:187: Fatal error: Client not shut down
before the deinit.`
This caused to a control flow issue when attempting to download the
default kernel during `container system start` and, under certain
conditions (e.g., network latency), encountering the timeout error
`HTTPClientError.connectTimeout`.
To address this, `client.execute()` is now wrapped in a do/catch to
ensure `shutdown()` is always called on both success and error paths.
Also I've added an explicit timeout configuration (30s connect, no read
timeout) to better accommodate large file downloads.
## Type of Change
- [x] New feature
## Description
Add option to force kernel setting and tests for CLI `kernel set`.
Related to https://github.com/apple/container/pull/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>