Add span uri

[Yicheng-Lu-llll]

TL;DR

This is part of Flytekit Metrics Exploration

This PR(also highlighted in green):

• adds span uri field to NodeExecutionEvent and NodeExecutionClosure.
• adds a new endpoint GetFlyteKitMetrics.

Flytekit Metrics Exploration includes:

• flytekit: https://github.com/flyteorg/flytekit/pull/1683

• flyteplugins: https://github.com/flyteorg/flyteplugins/pull/361

• flyteidl: https://github.com/flyteorg/flyteidl/pull/415

• flytepropeller: https://github.com/flyteorg/flytepropeller/pull/577

• flyteadmin: https://github.com/flyteorg/flyteadmin/pull/575

Type

• [ ] Bug Fix
• [ ] Feature
• [ ] Plugin

Are all requirements met?

• [ ] Code completed
• [ ] Smoke tested
• [ ] Unit tests added
• [ ] Code documentation added
• [ ] Any pending items have an associated Issue

Complete description

How did you fix the bug, make the feature etc. Link to any design docs etc

Tracking Issue

Remove the 'fixes' keyword if there will be multiple PRs to fix the linked issue

fixes https://github.com/flyteorg/flyte/issues/

Follow-up issue

NA OR https://github.com/flyteorg/flyte/issues/

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[codecov[bot]]

Codecov Report

Merging #415 (0d7bea7) into master (e506206) will increase coverage by 2.55%. The diff coverage is n/a.

:exclamation: Current head 0d7bea7 differs from pull request most recent head 1cfa4ee. Consider uploading reports for the commit 1cfa4ee to get more accurate results

@@            Coverage Diff             @@
##           master     #415      +/-   ##
==========================================
+ Coverage   75.92%   78.48%   +2.55%     
==========================================
  Files          18       18              
  Lines        1458     1250     -208     
==========================================
- Hits         1107      981     -126     
+ Misses        294      212      -82     
  Partials       57       57              

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see 18 files with indirect coverage changes