feat(query engine): introduce schema and plan

[forshev]

Description

• Add extractor executor - it extracts fields from document column and passes it to the next executors as a separate column
• Introduce Schema abstraction
• Introduce Plan abstraction

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[github-actions]

❌ PR Title Validation Failed
Please refer to CONTRIBUTING.md

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.24437% with 49 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.18%. Comparing base (e02c3a5) to head (603d02a).

Files with missing lines	Patch %	Lines
pkg/seqproxyapi/v1/mappings.go	22.22%	14 Missing ⚠️
query/plan/plan.go	91.48%	8 Missing ⚠️
pkg/storeapi/mappings.go	61.11%	7 Missing ⚠️
proxy/search/stream_search.go	82.50%	7 Missing ⚠️
proxyapi/grpc_complex_search.go	0.00%	6 Missing ⚠️
query/plan/ops.go	64.28%	5 Missing ⚠️
query/exec/merger.go	80.00%	1 Missing ⚠️
storeapi/grpc_stream_search.go	97.61%	1 Missing ⚠️

Additional details and impacted files

@@                   Coverage Diff                    @@
##           0-column-abstraction     #565      +/-   ##
========================================================
+ Coverage                 77.02%   77.18%   +0.15%     
========================================================
  Files                       249      253       +4     
  Lines                     18910    19085     +175     
========================================================
+ Hits                      14566    14730     +164     
- Misses                     4344     4355      +11     

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