GH-1022 android: enable zoom without on-screen controls

[reznej]

Platforms affected

Android

Motivation and Context

Closes Issue #1022

Description

This change adds an settable option zoomcontrols in addition to zoom at initialisation of the Inappbrowser instance. This enables a separation between zoom-controls (pinch-to-zoom) and additionally showing zoom-buttons to manually adjust zooming.

Testing

Ran manual tests with different combinations for parameters zoom and zoomcontrols.

Checklist

• [x] I've run the tests to see all new and existing tests pass
• [x] I added automated test coverage as appropriate for this change
• [x] Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• [x] 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)
• [x] I've updated the documentation if necessary