refactor: Use Java 9+ APIs instead of outdated/3rd-party APIs

[valfirst]

Change list

• Use Java 9 convenience factory methods for collections instead of Guava Collections
• Use Map.entry(..) instead of new AbstractMap.SimpleEntry<>(..)
• Use java.util.Objects.requireNonNull(..) (actually available since Java 7) instead of Guava Preconditions.checkNotNull(..)
• Deprecate MobileCommand.prepareArguments(..) in favour of Map.of(..)
• Use java.util.function.Function instead of AppiumFunction
• Replace !Optional.isPresent() with Optional.isEmpty()

Types of changes

What types of changes are you proposing/introducing to Java client?

• No changes in production code.
• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)