Add environment variables to execution spec

[pingsutw]

TL;DR

blocked by flyteorg/flyteidl#400
Add environment variables to execution spec, allowing people to add env at execution time

• Create execution with environment variables
• Override environment variables when relaunching
• Override environment variables when recovering

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

^^^

Tracking Issue

flyteorg/flyte#2447

Follow-up issue

NA

[codecov]

Codecov Report

Merging #556 (9259cac) into master (507ad44) will increase coverage by 1.54%.
The diff coverage is 75.00%.

❗ Current head 9259cac differs from pull request most recent head 4b738f8. Consider uploading reports for the commit 4b738f8 to get more accurate results

@@            Coverage Diff             @@
##           master     #556      +/-   ##
==========================================
+ Coverage   58.39%   59.94%   +1.54%     
==========================================
  Files         168      168              
  Lines       16093    13179    -2914     
==========================================
- Hits         9398     7900    -1498     
+ Misses       5858     4441    -1417     
- Partials      837      838       +1     

Flag	Coverage Δ
unittests	?

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Impacted Files	Coverage Δ
pkg/manager/impl/util/shared.go	68.52% <33.33%> (+3.01%)	⬆️
pkg/workflowengine/impl/prepare_execution.go	86.66% <100.00%> (+1.66%)	⬆️

... and 153 files with indirect coverage changes

[pingsutw]

blocked by IDL pr flyteorg/flyteidl#400