Replace okhttp / app state monitor

[z4kn4fein]

Describe the purpose of your pull request

This PR contains the following:

• Replaced the direct okhttp dependency with java.net.HttpURLConnection.
• Added the option to let the SDK watch for application state changes. It can switch between online and offline modes based on whether the application is in the foreground/background and on network availability.

Breaking changes

• The option to set a custom OkHttpClient was removed. Instead, a new HttpOptions was added to control HTTP timeouts and HTTP proxy configuration.

Security (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.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
1 Accepted issue

Measures
0 Security Hotspots
87.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud