allow environment variables for remove_token_from_body_when_cookies_used

[usu]

#940 introduced a new config option to enable response body when cookies are used:

remove_token_from_body_when_cookies_used: false

However, currently environment variables cannot be used to control this config. An error Environment variables "bool:JWT_REMOVE_TOKEN_FROM_BODY" are never used is thrown. After this PR, this option can also be used as following:

remove_token_from_body_when_cookies_used: '%env(bool:JWT_REMOVE_TOKEN_FROM_BODY)%'

[chalasr]

Thanks for the PR. Did you actually test it? I suspect this is not enough to properly support setting it via an env variable:
https://github.com/symfony/symfony/blob/043257f6fc1fceb28bc0c37c59f2bea4d9c8d79d/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php#L1945

[usu]

I tested successfully with my own application. Symfony DI automatically resolves the environment parameters when generating the DI factories. I assume this is the reason why environment variables already work for all the other config options.

Happy to provide a test, but couldn't find a good test to hook into or to copy from. There was no test provided when introducing #940 and couldn't really find a test that already utilizes environment variables for other config options.

[usu]

Hi @chalasr, anything you'd want me to add to this PR to make this mergeable?

[chalasr]

Thank you @usu.