Add an example to illustrate the use of `authz` package

[easwars]

We have an authz implementation which is split up as the API and the engine.

The API supports two ways of specifying the authorization policy: as a static string, or as a file to watch. The second method supports online updates to the policy.

We should have examples which illustrates the use of both.

Existing tests can serve as good starting point to understand the usage of the API.

[zasweq]

This issue was partially fixed by #5920, as this PR demonstrated an example through a hardcoded string. The file to watch section still needs to be addressed, as that opens up a different way of technically updating the policy in that case.

[shashank-priyadarshi]

Hi @ginayeh , I can work on this!

[arvindbr8]

@shashank-priyadarshi -- thanks! Assigning this to you.

PS: please make sure that the issue is assigned to you while you are actively working on it. This would make sure we dont have multiple contributors working on the same issue

[v-sreejith]

Hi @arvindbr8, I would like to contribute.