Added pflag for stow config in storage

[yindia]

TL;DR

Currently we are not generating pflag for stow config that means we are only able to pass sandbox storage config via flags.

• Added pflag for stow config

# New flags 
$  --stow.kind S3 --stow.config key=value,key2=val2

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/

[EngHabu]

Thank you!

[yindia]

@EngHabu Do you know why test are failing ?

[codecov]

Codecov Report

Merging #95 (3ac2955) into master (9f637fd) will decrease coverage by 0.30%.
The diff coverage is 44.44%.

@@            Coverage Diff             @@
##           master      #95      +/-   ##
==========================================
- Coverage   66.84%   66.53%   -0.31%     
==========================================
  Files          59       59              
  Lines        2817     2824       +7     
==========================================
- Hits         1883     1879       -4     
- Misses        789      799      +10     
- Partials      145      146       +1     

Flag	Coverage Δ
unittests	64.89% <50.00%> (-0.35%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
storage/config.go	60.00% <ø> (ø)
storage/config_flags.go	48.64% <37.50%> (-4.69%)	⬇️
storage/stow_store.go	73.01% <100.00%> (ø)
cache/auto_refresh.go	77.67% <0.00%> (-6.25%)	⬇️
sets/generic_set.go	94.56% <0.00%> (+1.08%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9f637fd...3ac2955. Read the comment docs.