[Access] Make WebSocket responses from data providers consistent with Access REST API responses

[UlyanaAndrukhiv]

Closes: #6775

Note: this PR should be merged after #6766

Context

This pull request updates the WebSocket data providers to utilize the same models and response converters used by the Access REST API. By aligning the data processing logic, responses from WebSocket and REST API endpoints will now have consistent structure and content. Updated and added new unit tests to validate shared model usage.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 60.18692% with 213 lines in your changes missing coverage. Please review.

Project coverage is 41.04%. Comparing base (0310dfd) to head (3f2906f).

Files with missing lines	Patch %	Lines
...e/access/rest/common/models/mock/link_generator.go	14.37%	129 Missing and 2 partials ⚠️
.../rest/websockets/data_providers/events_provider.go	73.72%	22 Missing and 9 partials ⚠️
...ockets/data_providers/account_statuses_provider.go	76.78%	18 Missing and 8 partials ⚠️
.../rest/websockets/data_providers/blocks_provider.go	59.45%	10 Missing and 5 partials ⚠️
engine/access/rest/router/router.go	0.00%	5 Missing ⚠️
engine/access/rest/http/routes/blocks.go	70.00%	3 Missing ⚠️
...e/access/rest/websockets/data_providers/factory.go	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6802      +/-   ##
==========================================
+ Coverage   40.98%   41.04%   +0.05%     
==========================================
  Files        2079     2087       +8     
  Lines      183922   184387     +465     
==========================================
+ Hits        75382    75681     +299     
- Misses     102240   102364     +124     
- Partials     6300     6342      +42     

Flag	Coverage Δ
unittests	41.04% <60.18%> (+0.05%)	⬆️

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