[azure core]: Add linting rules for explicit `@action`

- Add a warning if a reused 'post' action operation would change the action suffix
`myNewAction is someInterface.myOldAction; // action suffix changed to myNewAction`
- Consider adding a warning if `@action(actionSuffix)` is not added to post operations

Start by locating the Azure Core linting rules and the code that handles reused post action operations. Check how action suffixes are resolved and how explicit @action annotations are detected; done means warnings cover the changed suffix case and the missing annotation case described in the issue.

Written by the indexing model from the issue text.