feat: add stripe test key fields to settings model

[shreyanshdwivedi]

Fixes #6321

Short description of what this resolves:

Currently, there are only stripe client ID, secret key and publishable key in settings model, there should be test keys fields and they should be used when Debug is true

Changes proposed in this pull request:

• adds stripe test keys to settings model
• need to add a check to use these keys is debug is true

Checklist

• I have read the Contribution & Best practices Guide and my PR follows them.
• My branch is up-to-date with the Upstream development branch.
• The unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

• All the functions created/modified in this PR contain relevant docstrings.

[codecov]

Codecov Report

Merging #6322 into development will increase coverage by <.01%.
The diff coverage is 66.66%.

@@               Coverage Diff               @@
##           development    #6322      +/-   ##
===============================================
+ Coverage        65.26%   65.26%   +<.01%     
===============================================
  Files              287      287              
  Lines            14713    14721       +8     
===============================================
+ Hits              9602     9608       +6     
- Misses            5111     5113       +2

Impacted Files	Coverage Δ
app/api/helpers/payment.py	27.52% <0%> (-0.52%)	⬇️
app/models/setting.py	90.86% <100%> (+0.2%)	⬆️
app/api/schema/settings.py	100% <100%> (ø)	⬆️

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[shreyanshdwivedi]

@CosmicCoder96 made the requested changes. Please have a look

[shreyanshdwivedi]

@iamareebjamal @mrsaicharan1 @uds5501 please review