refactor: Isolate base Android functionality (#901)

BREAKING CHANGE: Removed androidHelpers export. Corresponding methods are now integrated into the driver
BREAKING CHANGE: Removed webviewHelpers export. Corresponding methods are now integrated into the driver
BREAKING CHANGE: Removed redundant exports related to io.appium.settings.
BREAKING CHANGE: Removed deprecated APIs related to launchApp/closeApp/reset
BREAKING CHANGE: Removed the unused unlocker property from the driver.

The mixin typesystem has been aligned. There are no explicit mixin definitions, which basically duplicate each method signature. Instead all types are now provided next to method definitions.

Improved grouping of different commands. Made it more explicit which of them are designed for export and which are just internal helpers

Improved helper methods design, so they don't need to retrieve driver-specific properties (like log or adb) via command line args, but use this context and explicit binding instead.

Marked legacy JWP touch-related methods as deprecated. They must be eventually replaced with proper W3C implementations.

Removed unused declarations for non-implemented methods.

Author: mykola-mokhnach