KZL-547 - Update validateSpecifications signature to take index and collection

[Aschen]

What does this PR do?

Before the method ValidateSpecifications didn't take an index an a collection in parameters and could be used for any collection.
This PR change the signature to match the rest of the collection controller. The method now take an index and a collection in addition to the specifications for this collection.

I also modify the UpdateSpecifications method. The method was taking an index and collection in parameter but it didn't scope the specifications to the collection.

Related PR: https://github.com/kuzzleio/sdk-javascript/pull/318, https://github.com/kuzzleio/sdk-go/pull/211, https://github.com/kuzzleio/sdk-c/pull/13, https://github.com/kuzzleio/sdk-cpp/pull/11, https://github.com/kuzzleio/sdk-java/pull/13, https://github.com/kuzzleio/documentation-V2/pull/51

How should this be manually tested?

• Step 1: Run tests ./test.sh

[codecov-io]

Codecov Report

Merging #211 into 1-dev will decrease coverage by 0.14%. The diff coverage is 66.66%.

@@            Coverage Diff             @@
##            1-dev     #211      +/-   ##
==========================================
- Coverage   88.97%   88.82%   -0.15%     
==========================================
  Files         243      243              
  Lines        4370     4384      +14     
==========================================
+ Hits         3888     3894       +6     
- Misses        454      458       +4     
- Partials       28       32       +4

Impacted Files	Coverage Δ
collection/validate_specifications.go	69.23% <57.14%> (-18.27%)	:arrow_down:
collection/update_specifications.go	91.3% <80%> (-8.7%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update a812be3...ec66f08. Read the comment docs.