feat: change service and version discovery

[juliapampus]

What this PR changes/adds

1. Allows .well-known endpoint to be located at base and not host URL
2. Changes service discovery via DID document, allowing for CatalogService and DataService (Connector)
3. Move Sec 5.4.5 to Sec 4

Why it does that

Address requirements of adopters:

• flexibility in service discovery
• flexibility in service deployment

while aiming for interoperability within and across dataspaces.

Further notes

Related issue #168 to be addressed in a future PR

Linked Issue(s)

Relates #146

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[jimmarino]

Looks good, just some minor wording fixes.

[lgblaumeiser]

Love that 😃

Two suggestion, though, if I may.

• An explicit remark in the did document section, that the service reference may be enhanced with further properties is not necessary but would help in adoption, as some discussion might be avoided.
• Perhaps it is worth a thought, that for a placement of the dspace-version endpoint not according to the rfc8615, the .well-known path part could be omitted, as this would potentially prevent discussions about the "wrong" adoption of the rfc.

[arnoweiss]

Love that 😃

Two suggestion, though, if I may.

• An explicit remark in the did document section, that the service reference may be enhanced with further properties is not necessary but would help in adoption, as some discussion might be avoided.
• Perhaps it is worth a thought, that for a placement of the dspace-version endpoint not according to the rfc8615, the .well-known path part could be omitted, as this would potentially prevent discussions about the "wrong" adoption of the rfc.

We discussed both.

• The first suggestion is better placed in the best practices. I'll update those to the state of the spec as soon as this PR is merged. (Adjust section on versioning and deployment BestPractices#16)
• That would mean that the application logic implementing the endpoint would have to be aware about how it's deployed. And that's something that we're trying to avoid altogether with this PR.

[matbmoser]

Really good idea! Thank you!