allow BuildVariables variables options

[dmlond]

in BuildVariables, I can create, update, and delete a variable with options that include environment_scope. I can get a variable with a defined environment_scope only if a variable with the same name does not exist with a different environment_scope (including the default scope ''.
If I create the same variable with multiple environment scopes (including the default scope ""), all of the methods variable, create_variable, update_variable, and remove_variable raise an exception, even if I include options to update_variable and remove_variable.

*** Gitlab::Error::Conflict Exception: Server responded with code 409, message: There are multiple variables with provided parameters. Please use 'filter[environment_scope]'. Request URI: https://gitlab.dhe.duke.edu/api/v4/projects/7370/variables/FOO

nil

Gitlab ensures that the same variable can be defined with different environment scopes, so that a job that runs in one environment can use different values for the same variables (this is a 12factor design principle).

I am able to use the underlying client methods with ?filter[environment_scope]:

variable_scope='review-*'
g.create_variable(project_id, "FOO", "something")
g.create_variable(project_id, "FOO", environment_scope:variable_scope)
g.get("/projects/#{g.url_encode project_id}/variables/FOO?filter[environment_scope]=#{variable_scope}")
g.put("/projects/#{g.url_encode project_id}/variables/FOO?filter[environment_scope]=#{variable_scope}", options.merge(value: "NEW"))
g.delete("/projects/#{g.url_encode project_id}/variables/FOO?filter[environment_scope]=#{variable_scope}")

[dmlond]

ok, so I can update and remove a variable with an environment_scope using

g.update_variable(project_id, "FOO", "NEW", 'filter[environment_scope]':variable_scope)
g.remove_variable(project_id, "FOO", 'filter[environment_scope]':variable_scope)

So, really, the issue is that I cannot call

g.variable(project_id, key, 'filter[environment_scope]':variable_scope)