Add grpc endpoint to EN for transaction execution metrics

[janezpodhostnik]

ref: #5598

this adds a grpc endpoint that can be called to get metrics around transaction execution. The metrics include:

• block height
• tx id
• tx execution time in nanoseconds
• tx execution effort breakdown by computation kind

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 34.61538% with 170 lines in your changes missing coverage. Please review.

Project coverage is 41.41%. Comparing base (5e2d76f) to head (2464067).
Report is 160 commits behind head on master.

Files with missing lines	Patch %	Lines
...mputation/metrics/transaction_execution_metrics.go	0.00%	46 Missing ⚠️
engine/execution/rpc/engine.go	0.00%	31 Missing ⚠️
cmd/execution_builder.go	0.00%	28 Missing ⚠️
engine/access/mock/execution_api_client.go	0.00%	24 Missing ⚠️
engine/access/mock/execution_api_server.go	0.00%	18 Missing ⚠️
engine/execution/computation/metrics/collector.go	77.77%	11 Missing and 1 partial ⚠️
module/metrics/execution.go	0.00%	7 Missing ⚠️
cmd/execution_config.go	0.00%	2 Missing ⚠️
engine/execution/computation/metrics/provider.go	96.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6172      +/-   ##
==========================================
- Coverage   41.42%   41.41%   -0.01%     
==========================================
  Files        2021     2024       +3     
  Lines      143934   144193     +259     
==========================================
+ Hits        59620    59716      +96     
- Misses      78142    78303     +161     
- Partials     6172     6174       +2     

Flag	Coverage Δ
unittests	41.41% <34.61%> (-0.01%)	⬇️

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[peterargue]

looks good. mostly testing and stylistic comments