[ORB-224] partial updates for datasets

[mclcavalcante]

Support updates on datasets API to name and sinks ids without requiring the other fields to be provided in the JSON body:

Both cases follow the rules:

• If it is informed, the new one must overwrite the old one
• If it is omitted, the old one must be maintained.
• If it is informed with empty or invalid values, an error must be raised informing that the attribute doesn't match the pattern required.

[codecov-commenter]

Codecov Report

Base: 64.29% // Head: 64.36% // Increases project coverage by +0.07% 🎉

Coverage data is based on head (6ea0432) compared to base (d646d28).
Patch coverage: 89.47% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2144      +/-   ##
===========================================
+ Coverage    64.29%   64.36%   +0.07%     
===========================================
  Files           61       61              
  Lines         4638     4650      +12     
===========================================
+ Hits          2982     2993      +11     
- Misses        1656     1657       +1     

Impacted Files	Coverage Δ
policies/api/grpc/endpoint.go	47.72% <ø> (ø)
policies/postgres/policies.go	76.81% <ø> (ø)
policies/api/http/endpoint.go	94.87% <66.66%> (-1.13%)	⬇️
policies/api/http/requests.go	93.75% <100.00%> (+0.20%)	⬆️
policies/policy_service.go	88.80% <100.00%> (+0.54%)	⬆️

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[lpegoraro]

LGTM