Optimize the static err definitions

Is your feature request related to a problem? Please describe.
Static error types defined in scorecard/checks/raw/errors.go or similar places are too scattered.

Solution: Perhaps they could be more generalized. For example, we can simply define something invalid as errInvalid, with a reason string to specify why it's invalid when we throw the error; rather than defining separate errInvalidArgType, errInvalidArgLength, and errInvalidGitHubWorkflow. (proposed by @laurentsimon)

Start with checks/raw/errors.go and inspect the similar static error definitions mentioned in the issue. Determine how the proposed generalized errors would apply across those locations without changing reported behavior. Done means the scattered definitions are consistently reduced and the existing project checks still pass.