Add/proof gen time

[lpoli]

Changes

This PR will record time taken to generate challenge proof and also will record file size.

Fixes

Tests

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• 0chain:
• gosdk:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...

[codecov-commenter]

Codecov Report

Merging #978 (896d612) into staging (3e2024d) will not change coverage.
The diff coverage is n/a.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@           Coverage Diff            @@
##           staging     #978   +/-   ##
========================================
  Coverage    26.18%   26.18%           
========================================
  Files           76       76           
  Lines         7744     7744           
========================================
  Hits          2028     2028           
  Misses        5444     5444           
  Partials       272      272           

Flag	Coverage Δ
Unit-Tests	26.18% <ø> (ø)

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[peterlimg]

LGTM

[service-0chain]

Manual system tests [success] with the following config

config	value
tests skipped	TRUE
system-tests	master
gosdk	NOT OVERRIDDEN
zboxcli	staging
zwalletcli	staging
0chain	staging
blobber	add/proof-gen-time
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	master
0proxy	staging
0search	staging