Upgraded mw-selenium to 1.x, following the docs at
https://doc.wikimedia.org/rubygems/mediawiki-selenium/file.UPGRADE.html
Created an `environments.yml` file, converted page object definitions to
use relative paths, and refactored references to the global `ENV` using
methods of `MediawikiSelenium::Environment`.
Upgraded commons_upload as well to resolve a dependency conflict on
mediawiki_api.
Paired with: Rummana Yasmeen <ryasmeen@wikimedia.org>
Bug: T99661
Change-Id: I2a05cd816ea43afb48157e5dbe1ae42c6c124f6b
