feat: avoid Instantiation of banker on pure packages

[Villaquiranm]

Related to #2192

• Trigger a panic if a p/ attempts to create a banker, but allow interaction with an already instantiated banker from r/.

Don't really know if this is the right approach. If you have another idea of how to implement this security check please let me know :)

Contributors' checklist...

• [ ] Added new tests, or not needed, or not feasible
• [ ] Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• [ ] Updated the official documentation or not needed
• [ ] No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• [ ] Added references to related issues and PRs
• [ ] Provided any useful hints for running manual tests
• [ ] Added new benchmarks to generated graphs, if any. More info here.