fix: show only grpc error

[migmartri]

Shows just the gRPC error not the whole wrapped chain to the user for expected gRPC errors.

Examples

Before

$ go run main.go --insecure org api-token create --name test
ERR creating API token: creating API token: rpc error: code = AlreadyExists desc = duplicated: name already taken

after

$ go run main.go --insecure org api-token create --name test
ERR duplicated: name already taken

before

$ go run main.go --insecure org api-token create --name test_foo
ERR creating API token: creating API token: rpc error: code = InvalidArgument desc = validation error: "test_foo": a lowercase RFC 1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')

after

$ go run main.go --insecure org api-token create --name test_foo
ERR validation error: "test_foo": a lowercase RFC 1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')

fixes #1207