Add env_var and file as supported types for CI variables. Variables of
type file expose to users existing gitlab-runner behaviour - save
variable value into a temp file and set the path to this file in an ENV
var named after the variable key.

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/46806.

This reverts commit f5201a81, reversing
changes made to 48e6db0d.

This reverts merge request !25293

This adds a concern that abstracts the concept of masking a variable,
including the RegEx for validation.

Updates specs to use new rails5 format.

The old format:
`get :show, { some: params }, { some: headers }`

The new format:
`get :show, params: { some: params }, headers: { some: headers }`

Signed-off-by: Rémy Coutable <remy@rymai.me>

Always use declared_params(include_missing: false)
so that we don't give nils for optional arguments

Removed all the unnecessary include of `WaitForAjax` and `ApiHelpers` in the specs.
Removed unnecessary usage of `api:true`

Signed-off-by: Rémy Coutable <remy@rymai.me>

Restore changes for api spec files

Fix error in rspec Users

Delete extra space Repositories-spec