[Access] Refactor REST Routes Package

[UlyanaAndrukhiv]

Closes: #6615

Context

This PR introduces a significant restructuring of the access/rest folder, enhancing modularity and clarity.

• The new organization separates http and WebSocket components into http and websockets directories, simplifying maintenance and readability.
• Common functionality is moved to the rest/common package.
• RouterBuilderimplementation is separated from all routes and moved to rest/router.
• Lists of http and ws routes are now in http_routes.go and ws_routes.go, respectively.
• The current v1/subscribe_events route is moved into the websocket/legacy folder to separate future WebSocket implementations.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 37.11790% with 144 lines in your changes missing coverage. Please review.

Project coverage is 41.19%. Comparing base (f44c7fb) to head (6be9cc4).

Files with missing lines	Patch %	Lines
...e/access/rest/http/request/get_execution_result.go	0.00%	24 Missing ⚠️
engine/access/rest/router/router_test_helpers.go	0.00%	22 Missing ⚠️
engine/access/rest/http/request/get_block.go	0.00%	14 Missing ⚠️
engine/access/rest/http/request/get_transaction.go	0.00%	11 Missing ⚠️
engine/access/rest/http/request/get_collection.go	0.00%	9 Missing ⚠️
...access/rest/websockets/legacy/websocket_handler.go	62.50%	6 Missing ⚠️
...ine/access/rest/http/request/create_transaction.go	0.00%	5 Missing ⚠️
engine/access/rest/http/request/get_account.go	0.00%	5 Missing ⚠️
...ne/access/rest/http/request/get_account_balance.go	0.00%	5 Missing ⚠️
engine/access/rest/http/request/get_account_key.go	0.00%	5 Missing ⚠️
... and 15 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6616      +/-   ##
==========================================
- Coverage   41.19%   41.19%   -0.01%     
==========================================
  Files        2052     2052              
  Lines      182215   182219       +4     
==========================================
- Hits        75072    75070       -2     
- Misses     100850   100856       +6     
  Partials     6293     6293              

Flag	Coverage Δ
unittests	41.19% <37.11%> (-0.01%)	⬇️

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[peterargue]

looks good. only comment is about switching to using strings for payload

[Guitarheroua]

LGTM