* introduce feature flags
* move config to webpack-helper
* remove package default
* add gating to frontendConfig and coreConfig
* add feature gating to PHP
* add flag to start command
* move code to Bootstrap.php
* remove flag from npm start
* add eslint rule
* add strict equal only rule
* update messages to use tokens
* update strictBinary to whitelistedFlag and add all tests
* update to correct messageId key
* add more tests
* highlight wrong flag
Seghir Nadir