feat: Added missing functionality to govDAO

[ajnavarro]

• Add a Voter interface to be able to implement different voting systems in the future
• Add members and an executor to add them
• Improve Render output a bit.
• Added tests
• Tidy up and remove unnecessary code

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.