Rake releases

## What's Changed * Preserve `ENV["TESTOPTS"]` when verbose is enabled

## What's Changed * Add `lib/rake/options.rb` to gemspec

Minor fixes and improvements.

Code quality improvements including useless condition removal, RAKEOPT documentation addition, JRuby assertion handling fixes, environmental variable name corrections, TaskArguments#deconstruct_keys handling for nil keys, and warning suppression during task execution.