client: merge ExecInspectResult with ExecInspect

The `ExecInspectResult` type was embedding `ExecInspect`, which is also
defined by the client, so there's no need to abstract it.

While updating, also;

- Rename `ExecID` to `ID`, to match the field-name returned by the API.
- Rename `Pid` to `PID`, to be in the right casing.
- Remove `json` labels, as option-types are not (un)marshaled to JSON.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration/internal/container/exec.go

@@ -77,12 +77,12 @@ func Exec(ctx context.Context, apiClient client.APIClient, id string, cmd []stri
 	}
 
 	// get the exit code
-	iresp, err := apiClient.ExecInspect(ctx, execID, client.ExecInspectOptions{})
+	inspect, err := apiClient.ExecInspect(ctx, execID, client.ExecInspectOptions{})
 	if err != nil {
 		return ExecResult{}, err
 	}
 
-	return ExecResult{ExitCode: iresp.ExitCode, outBuffer: &s.stdout, errBuffer: &s.stderr}, nil
+	return ExecResult{ExitCode: inspect.ExitCode, outBuffer: &s.stdout, errBuffer: &s.stderr}, nil
 }
 
 // ExecT calls Exec() and aborts the test if an error occurs.