Query by tag, tag property

# Summary
- Query by tag, tag property
- "Not Equal" predicate

## Tag Property
- Added "tag" value to the hash describing an element (`.../query/ViewMapper.java`)
- Added `getTagForView` to get the view's tag (if any).
- Support predicates for "tag" property in queries

Can be used as an alternative to an ID. Since anything can be a tag in Android, it can be utilized to be similar to `accessbilityIdentifier` in iOS.

Android allows assigning multiple tags to the view and get them by the index using `getTag(int index)`, but this implementation depends on "default" tag accessible via `getTag()`.

## Not Equal Predicate
Added `NOTEQUAL` predicate support (`.../query/ast/ComparisonOperator.java` and `.../query/ast/UIQueryASTPredicate.java`) to enable queries with "!=" and "<>" comparisons.
Modified `UIQuery.g` for the same.

## Formatting
- Remove trailing spaces in all touched files
- Fix blank lines (remove obsolete spaces) in all touched files