Add make target to fetch the default kernel (#33)

Replaces the `--install-dependencies` flag with the
`(enable/disable)-kernel-install` flag. If the flag is not passed - the
default behavior is prompting the user for a response.

Also adds a make target `install-kernel`

```
➜ bin/container system start
Verifying apiserver is running...
Installing base container filesystem...
No default kernel configured.
Install the recommended default kernel from [https://github.com/kata-containers/kata-containers/releases/download/3.17.0/kata-static-3.17.0-arm64.tar.xz]? [Y/n]: n
Please use the `container system kernel set --recommended` command to configure the default kernel

➜ bin/container system start --disable-kernel-install
Verifying apiserver is running...

➜ bin/container system start --enable-kernel-install
Verifying apiserver is running...
Installing kernel...

➜ bin/container system start --help

USAGE: container system start ... [--enable-kernel-install] [--disable-kernel-install]
...
  --enable-kernel-install/--disable-kernel-install
                          Specify if the default kernel should be installed or not.

```

---------

Signed-off-by: Aditya Ramani <a_ramani@apple.com>

.github/workflows/common.yml

@@ -63,7 +63,7 @@ jobs:
       - name: Test the container project
         run: |
           launchctl setenv HTTP_PROXY $HTTP_PROXY
-          make test integration
+          make test cleancontent install-kernel integration
         env:
           CONTAINER_REGISTRY_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           CONTAINER_REGISTRY_USER: ${{ github.actor }}