implement method for EvaluationResult protocol

[yuki-mt]

What is this PR for?

add method for EvaluationResult protocol to return detailed evaluation result to a client.
related to rekcurd/dashboard#55

This PR includes

• update grpc submodule to add result_path to EvaluationResultRequest grpc-proto#13
• implement EvaluationResult method
• make data for gRPC in get_io_by_type and get_score_by_type method
• rename EvaluateDetail EvaluateResultDetail
• now EvaluateDetail include input, label, EvaluateResultDetail
• remove initial_metadata = rpc.initial_metadata() because it is never used.

What type of PR is it?

Feature

What is the issue?

How should this be tested?

python -m unittest

[keigohtr]

Almost LGTM

[codecov-io]

Codecov Report

Merging #24 into master will increase coverage by 0.55%.
The diff coverage is 94.35%.

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
+ Coverage   87.46%   88.02%   +0.55%     
==========================================
  Files          16       16              
  Lines        1037     1152     +115     
==========================================
+ Hits          907     1014     +107     
- Misses        130      138       +8

Impacted Files	Coverage Δ
drucker/utils/__init__.py	77.89% <100%> (+3.53%)	⬆️
drucker/test/test_dashboard_servicer.py	100% <100%> (ø)	⬆️
drucker/test/dummy_app.py	78.57% <80%> (-4.77%)	⬇️
drucker/drucker_worker.py	81.81% <83.33%> (-0.73%)	⬇️
drucker/drucker_dashboard_servicer.py	96.1% <89.79%> (-2.97%)	⬇️

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[keigohtr]

LGTM