Add more Android configuration options

[irgendeinich]

Resolves #344

Details

Adds two new keys to the configuration prop:

• showSettingsMenu for hiding and showing the view settings button in the toolbar.
• customTitle for overriding the document title with a custom title that will be displayed.

Adds two new props to the PSPDFKitView:

• showNavigationButtonInToolbar for enabling and disabling showing a navigation button in the main toolbar.
• onNavigationButtonClicked for handling when this up button was clicked.

Acceptance Criteria

• When approved, right before merging, rebase with master and increment the package version in package.json, package-lock.json, samples/Catalog/package.json, and samples/NativeCatalog/package.json (see example commit: 1bf805f).
• Create a new release (and tag) with the new package version (see https://github.com/PSPDFKit/react-native/releases).

[radazzouz]

The newly added props are Android only. I tested the iOS Catalog and it runs great. This change does not impact iOS. The JS code also LGTM 👍

Here are a few suggestions:

1. On iOS we added the ability to add a custom title in Add toolbarTitle Javascript API to override the iOS toolbar title #255 and we named the configuration option toolbarTitle instead of customTitle. I would use the same naming in here for consistency.

2. I would also document the use of the custom title in a Catalog example.