feat: Add initial delay for polling feature configuration

[samuolis]

Description

• Added pollingDelayInMillis in initialize options, to declare delay for the first request of feature flags
• Added tests to cover this case

This should solve the issue of getting feature flags before the first polling even happened (Default delay is 5 mins, it is okay for polling but not okay for waiting for initial data)

Checklist

• [x] I have tested this code
• [x] I have added unit test to cover this code
• [x] I have updated the documentation (README.md and /website/docs)
• [x] I have followed the contributing guide

[netlify[bot]]

✅ Deploy Preview for go-feature-flag-doc-preview canceled.

Name	Link
🔨 Latest commit	e7202d3311c149f8e4c62131752d89b9bc8f279c
🔍 Latest deploy log	https://app.netlify.com/sites/go-feature-flag-doc-preview/deploys/66d6b83c86ba260008f03ea0

[samuolis]

@thomaspoignant Do this library need code duplication check on tests, because it is falling on already existing tests?

Edit: Changed sonar config to include those files, there was typo

[thomaspoignant]

@samuolis thanks for your pull request, it fixes an important problem from the provider.

I am currently away (taking some vacation), but I will look closely to your PR early September and we will be able to release a new version of the provider with this addition.

For the code duplication, this should not be a problem for test, thanks for the sonar fix 🙏

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.02%. Comparing base (eec11f3) to head (e7202d3). Report is 58 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2257   +/-   ##
=======================================
  Coverage   86.02%   86.02%           
=======================================
  Files         102      102           
  Lines        3743     3743           
=======================================
  Hits         3220     3220           
  Misses        399      399           
  Partials      124      124           

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[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[samuolis]

Sorry for such a delay, I missed this line somehow. I now see what was the problem, somehow the first API call was getting cancelled, now it works perfectly