feat: extend menus capabilities

[axel7083]

What does this PR do?

Thanks to @benoitf in #3938 (comment) I understood that it was possible to link a command to an item menu.

However, this features was only implemented for the Image List dashboard. I extended it to support the ContainersList dashboard as well.

Screenshot/screencast of this PR

Here is the contributes used to test this PR

...
  "contributes": {
    "commands": [
      {
        "command": "my.first.command",
        "title": "My First Extension: Hello World"
      }
    ],
    "menus": {
      "dashboard/container": [
        {
          "command": "my.first.command",
          "title": "My First Extension: Hello World"
        }
      ]
    }
  }
...

What issues does this PR fix or reference?

Partially fix #3938

How to test this PR?

[benoitf]

thanks for the contrib

I think we're missing tests for

ContributionActions.svelte (to check if we're executing commands with correct args, how not-serializable args are filtered out)

Would be also nice for ContainerList

[benoitf]

it looks like there is a regression in one of the existing unit test

[benoitf]

just a couple of nits but thanks again @axel7083 for this nice enhancement 🎉

[lstocchi]

Thanks @axel7083 !! 🚀