Added support for priority queues in switch configuration

[code-a1]

Support for simple switch priority queues in the configuration file can be useful to expand the existing exercises or for future exercises on this topic.

The priority queues number can be defined inside the topology file as follows:

...
    "switches": {
        "s1": { 
            "priority_queues": 8,
            /* Other parameters here */
     }
...

[github-actions]

Welcome to the project, @code-a1!

It looks like this is your first contribution. We noticed the DCO (Developer Certificate of Origin) check might fail if your commits aren't signed.

To fix this, please ensure every commit has a Signed-off-by: Name <email> line. You can do this automatically by using the -s flag:
git commit -s -m "Your message"

For existing commits, you can fix them with:
git commit --amend --signoff or git rebase -i HEAD~N --signoff (where N is the number of commits)
The Developer Community DCO guide also provides helpful tips on fixing DCO inconveniences. Setting a commit hook in the git repository will automate adding the DCO signoff.
See https://github.com/p4lang/governance/wiki/P4-DCO-Guidelines for information.

[Dscano]

Hi @code-a1 ,

As mentioned here you should "sign" your commits #719 (comment).

The PR you proposed only partially improves the tutorial exercises, since we don’t use priority_queues in any of them. Also, since this isn’t a P4 language feature but rather a BMv2 feature, it should be better contextualized if we want to include it.
Perhaps are you proposing this PR as a starting point to add a new exercise that uses priority_queues?