Minor corrections

[adams85]

Describe the purpose of your pull request

Bug fixes:

• Adjusts the browser and chrome-extension platforms to work correctly in web workers too.
  • Implements an IndexedDB-backed config cache and uses it when running in a web worker (as LocalStorage is not available in web workers).
  • Corrects DefaultQueryStringProvider to make it work in web workers (as window global variable is not available web workers.)
  • Also, adds a sample app which runs the SDK in a web worker.
• A bunch of minor corrections (especially to project and build configuration).

Breaking changes:

• Change SettingKeyValue to a plain object type. (Very low impact expected. It's unlikely that consumers create instances of this type but even then they may not use the ctor.)
• Change FlagOverrides to a plain object type. (Internal breaking change only.)
• Rename LocalStorageCache to LocalStorageConfigCache and ChromeLocalStorageCache to ChromeLocalStorageConfigCache. (Internal breaking change only.)

Related issues (only if applicable)

n/a

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.

[sonarcloud]

Quality Gate failed

Failed conditions
4.2% Duplication on New Code (required ≤ 3%)
D Reliability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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