(ios) Add InAppBrowserStatusBarStyle preference

[mrbberra]

Platforms affected

iOS

Motivation and Context

This allows apps that set a dark status bar background color using cordova-plugin-statusbar to set the status bar style when using the in app browser. Became necessary after GH-656.
Fixes: #728

Description

Adds the ability to set <preference name="InAppBrowserStatusBarStyle" value="lightcontent" /> in the config.xml file, so that the preferredStatusBarStyle becomes UIStatusBarStyleLightContent instead of UIStatusBarStyleDefault.

Testing

I created a test app and tried setting the InAppBrowserStatusBarStyle to "default", "lightcontent", and removing it alltogether. I didn't add any new automatic tests- not sure how.

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[dpa99c]

I've tested this with my test harness project and confirm it works as intended.

[mosabab]

I've tested this with my test harness project and confirm it works as intended.

Thanks for test and merges.

Does anyone add this <preference name="InAppBrowserStatusBarStyle" value="lightcontent" /> to config.xml (https://github.com/apache/cordova-docs/blob/master/www/docs/en/dev/config_ref/index.md) documents ?

If not, i will add a pull request to explain this in general Config.xml Docs.