Implement a query string flag override data source

[adams85]

Describe the purpose of your pull request

Based on a user request, adds a flag override data source that use the browser URL's query string as its source.

Note that this is meant to be an experimental feature, which, if works out, will probably be included in all the SDKs running in the browser.

Related issues (only if applicable)

https://trello.com/c/5zOq7X4K

Requirement checklist (only if applicable)

• I have covered the applied changes with automated tests.
• I have executed the full automated test set against my changes.
• I have validated my changes against all supported platform versions.
• I have read and accepted the contribution agreement.

[adams85]

I'd like a text review for this new documentation text: https://github.com/configcat/react-sdk/pull/63/files#diff-a2a171449d862fe29692ce031981047d7ab755ae7f84c707aef80701b3ea0c80R13-R25

And a UX review for

• the naming of the new public APIs (createFlagOverridesFromQueryParams and IQueryStringProvider),

• the parameter name format

  • default prefix: cc-,
  • "force value to be interpreted as string" suffix: ;str

  Example: &cc-myFeatureFlag;str=true

[github-actions]

Head's up @configcat/ux-qa-team - someone needs a UX review!

[github-actions]

Head's up @configcat/text-reviewers - someone needs a text review!

[sonarqubecloud]

Quality Gate failed

Failed conditions
20.1% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud