GitLab Integration: Add support to disable variable expansion

[JanHolger]

Feature description

Sometimes secrets can contain "$" in them and GitLab would expand those variables because you set raw to false when creating the variables. Since variable expansion is barely ever useful and will more likely cause issues (for example: harbor robot accounts contain $ in the username) it would be great to also have an option to turn that off like the existing options to turn on masking and protection.

Why would it be useful?

As explained above having secrets that contain $ will cause issues unless you escape them with $$ but then you'll need 2 secrets in infisical because other systems consuming the same secret will not expand the $$ to $.