[NT-1760] Adding feature flag for segment

[singhhari]

📲 What

Adding a feature flag for Segment and implementing it within out Analytics client.

🤔 Why

This is simply an additional layer of control on the clients behavior in our environments.

🛠 How

• Added the flag on Flipper
• Decoding it on iOS
• Implementing it into the Segment client

[jgsamudio]

LGTM! Thanks Hari!

[codecov]

Codecov Report

Merging #1376 (c670788) into master (056e871) will decrease coverage by 3.41%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##           master    #1376      +/-   ##
==========================================
- Coverage   89.27%   85.85%   -3.42%     
==========================================
  Files         734     1103     +369     
  Lines       66260    96079   +29819     
==========================================
+ Hits        59152    82489   +23337     
- Misses       7108    13590    +6482     

Impacted Files	Coverage Δ
Library/Feature.swift	0.00% <0.00%> (ø)
Library/Tracking/Segment.swift	73.91% <66.66%> (-1.09%)	⬇️
Library/Extensions/Feature+Helpers.swift	100.00% <100.00%> (ø)
Library/Extensions/Feature+HelpersTests.swift	100.00% <100.00%> (ø)
...ry/ViewModels/FeatureFlagToolsViewModelTests.swift	100.00% <100.00%> (ø)
Library/Tracking/MockTrackingClient.swift	90.47% <0.00%> (-9.53%)	⬇️
...ollers/ShippingRulesTableViewControllerTests.swift	100.00% <0.00%> (ø)
... and 371 more

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