object/search: Refactor storage policy processing

[cthulhu-rider]

• starts #1803
• prepares the way for #1988 (#2692)

[carpawell]

Some conflict is here.

[roman-khimov]

Post-0.41.0.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 39.77273% with 53 lines in your changes are missing coverage. Please review.

Project coverage is 23.65%. Comparing base (561ea49) to head (abbf849). Report is 7 commits behind head on master.

Files	Patch %	Lines
pkg/services/object/search/container.go	44.82%	25 Missing and 7 partials :warning:
cmd/neofs-node/object.go	0.00%	14 Missing :warning:
cmd/neofs-node/policy.go	69.23%	2 Missing and 2 partials :warning:
pkg/services/object/search/service.go	0.00%	3 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2806      +/-   ##
==========================================
+ Coverage   23.63%   23.65%   +0.01%     
==========================================
  Files         769      769              
  Lines       44594    44516      -78     
==========================================
- Hits        10541    10531      -10     
+ Misses      33202    33131      -71     
- Partials      851      854       +3     

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