feat: Add runtime flag to container create and run commands (#1049)

[iko1]

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Motivation and Context

Fixes #1049

• Add --runtime option for Flags.Management
• Apply runtime handler in containerConfigFromFlags
• Update command-reference.md doc

Testing

• Tested locally
• Added/updated tests
• Added/updated docs

[jglogan]

@iko1 Is there a use case for exposing this flag?

I'd think we'd want to expose it once another runtime helper exists somewhere, and that that helper needs to be invoked explicitly via a flag like this.

[iko1]

@iko1 Is there a use case for exposing this flag?

I'd think we'd want to expose it once another runtime helper exists somewhere, and that that helper needs to be invoked explicitly via a flag like this.

@jglogan , thanks for the review

If @katiewasnothere has a concrete use case for exposing it, I’m happy to update the PR accordingly; otherwise I’ll go ahead and close this and revisit when such a use case comes up.

[jglogan]

@iko1 I'll check with @katiewasnothere

[katiewasnothere]

@iko1 Hi! One example use case for this would be if someone wanted to make a FreeBSD runtime plugin for container (see this open issue) or a runc runtime plugin. It would be nice for us to be able to start and manage those containers through the same CLI commands as opposed to needing a CLI plugin to do so.