fix(validation): avoid policy evaluation on consumer side after agreement

[ndr-brt]

What this PR changes/adds

Changes contract validation on consumer side when it receives the "confirmed" message from the provider, at this point the agreement is already reached and there should be only a formal validation of the id and the policy, no need to evaluate the latter.

Why it does that

It was an unnecessary evaluation.

Further notes

• renamed the validate method to validateConfirmed to have a clear distinction on what's the purpose of the method avoiding confusion with the others.
• refactored ContractId to a more object oriented one.
• made validateConfirmed returns a Result, so the caller can obtain a detail on what was the problem.

Linked Issue(s)

Closes #1975

Checklist

• added appropriate tests?
• performed checkstyle check locally?
• added/updated copyright headers?
• documented public classes/methods?
• added/updated relevant documentation?
• assigned appropriate label? (exclude from changelog with label no-changelog)
• formatted title correctly? (take a look at the CONTRIBUTING and styleguide for details)

[codecov-commenter]

Codecov Report

Base: 64.31% // Head: 64.56% // Increases project coverage by +0.24% 🎉

Coverage data is based on head (32365c0) compared to base (58f6aa1).
Patch coverage: 54.90% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2068      +/-   ##
==========================================
+ Coverage   64.31%   64.56%   +0.24%     
==========================================
  Files         780      783       +3     
  Lines       16564    16638      +74     
  Branches     1077     1078       +1     
==========================================
+ Hits        10653    10742      +89     
+ Misses       5461     5442      -19     
- Partials      450      454       +4     

Impacted Files	Coverage Δ
...aceconnector/ids/core/IdsCoreServiceExtension.java	0.00% <0.00%> (ø)
.../dataspaceconnector/sql/lease/SqlLeaseContext.java	0.00% <0.00%> (ø)
...actdefinition/ContractDefinitionApiController.java	95.55% <ø> (-0.10%)	⬇️
...taspaceconnector/sql/assetindex/SqlAssetIndex.java	0.00% <0.00%> (ø)
...ctdefinition/store/SqlContractDefinitionStore.java	0.00% <0.00%> (ø)
...negotiation/store/SqlContractNegotiationStore.java	5.17% <0.00%> (+0.14%)	⬆️
...tor/sql/policy/store/SqlPolicyDefinitionStore.java	0.00% <0.00%> (ø)
...transferprocess/store/SqlTransferProcessStore.java	0.00% <0.00%> (ø)
...iation/ProviderContractNegotiationManagerImpl.java	90.55% <66.66%> (ø)
...ract/validation/ContractValidationServiceImpl.java	60.93% <66.66%> (+8.55%)	⬆️
... and 45 more

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