Implement 0.8 spec

[icidasset]

This PR implements the 0.8.1 spec and thus closes #47.

The biggest change involves attenuations. I've taken the capability types, revised them to the new spec, taken them out of the types.ts module and split them up in several parts under src/capabilities/, plus the top level src/capabilities.ts module. Each module in there has the types, utility functions, encoders/decoders, type checking functions, etc.

Notes:

• Introduced semver version parsing in the compatibility module
• Legacy UCAN version 0.0.1 has been changed to 0.3.0
• Categorised things in the types module
• Moved WNFS things to tests, should be moved to webnative in the future.
• Moved tests/emailCapabilities.ts to tests/capabilities/email.ts

Todo/Questions:

• Do we need additional utility functions for the capabilities?
• Do we need more spec enforcing? (ie. such as enforcing the URI format for capability resource pointers)
• Does the spec enforcing cause any issues anywhere? (eg. check encoding/decoding of URI format of resource pointers)
• Did I miss anything in the spec? (go over spec once more)

[icidasset]

Should we have functions for wnfs and email too? I realise they're not part of the spec, but could be helpful?

[matheus23]

Hmm 🤔 For now I think we should keep them outside the public API 👍

[icidasset]

I think this PR also partially implements #43? It's got some utility functions for creating prf capabilities and for superuser* resources/abilities.

In capability checking it essentially allows you to "forward" who the "originator" is for all capabilities without having to mention concrete capabilities.

@matheus23 Do you think that after my 0.8 changes we need to adjust the CapabilitySemantics parsing/delegating?

[bgins]

Looks great! Love how the customizable capability semantics have come out here. 💯 🎉

[icidasset]

I'll wait for @matheus23 to give this a look as well.

[matheus23]

Looking good! :) Thanks for reorganizing a bit & cleaning stuff up, too 🙏

@matheus23 Do you think that after my 0.8 changes we need to adjust the CapabilitySemantics parsing/delegating?

Yep! But we should do that in another PR. Let's ship incrementally 🚢
If you have any questions about how that hairy capabilities iterator works today, feel free to ping me in discord.

Also we'll likely want some tests for this stuff, but I think that makes most sense with the new capability semantics/parsing stuff from above 👆