Spec 3.2 support with format v5 and third party

[StevenLeRoux]

• Update version support to handle block versions 4 and 5
• Add 'check all' query type support (block version 4)
• Add 'reject if' query type support (block version 5)
• Implement third-party blocks protobuf definitions
• Add third-party block Go types and structures
• Implement third-party block creation and verification
• Implement public key interning feature
• Add parser support for check all/reject if syntax
• Add comprehensive tests for all new features

[Geal]

@StevenLeRoux hey, glad to see your interest in contributing to biscuit-go. Unfortunately what you are attempting will be way too large and conflict with existing work to implement third party blocks. This is a complex and subtle part of biscuit that requires knowing a lot of context on how it is built and what needs to refactor.
The changes to support check all and reject if will be most welcome, but that has to come after the datalog engine refactoring needed for 3rd party block support.
On what timeline would you need biscuit-go to support the recent features?

[StevenLeRoux]

Hey ! thanks for pointing me to #95
No rush needed here. I wanted to integrate Biscuit in a go codebase, but I think I can work around it for now. You can close this PR.

Is there any way I can help improve this Go library?

[Geal]

Good to know! What would be immensely helpful is some integration tests that reproduce some of what you use (doesn't need to expose anything sensitive) to make sure we won't introduce regressions. The library currently does not have a lot of tests. Opinions on the API surface and its UX also help a lot