(android) New 'enablethirdpartycookies' option and code clean-ups

[fquirin]

Platforms affected

Android.

Motivation and Context

• Third party cookies should be configurable and not just simply on by default
• I've done some additional code improvements to better handle resources
• Fixed a type and some potentially confusing, redundant code

Description

• Third party cookies are often used for tracking and thus should at least be configurable.
• The code for loading drawables kept repeating so I decided to introduce a function to handle it and making it easier to adapt in case of changes. In addition I thought it was useful to handle all required resources as static variables at the top.
• 'hardwarebackbutton' was misspelled, so I fixed that.
• 'showWebPage' redefined some defaults that were already defined at the top which could be very confusing if the default has to be changed in the future.
• Minor code clean-ups for better readability.

Note: I noticed there is a lot more potential for optimizing the code. Android Studio itself is already pointing out several simplifications. If there is enough interest I'd consider creating another PR :-).

Testing

• Built the app with the new version
• Checked if browser loads as expected
• Changed third party cookie support with new option
• Testes results with https://www.whatismybrowser.com/detect/are-third-party-cookies-enabled
• All working as expected :-)

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