Add an ability to provide additional environment variables for commanline

[baev]

[andrejska]

Will be this feature also include possibility to pass options flag, like --config? As this feature has been implemented: https://github.com/allure-framework/allure2/issues/378 Now we have possibility to have allure configuration file in project, but it cannot be used in scripted pipelines with allure jenkins plugin :(

[eroshenkoam]

@andrejska no, it's about variables, I will make another ticket for your request

[mikesalvia]

--config option was added in PR #204 it is still under review.

[mikesalvia]

@andrejska this should address your request but doesn't allow for env vars