fix: return auth none when no auth is configured for smtp + scopes in grpc response (#11554)

# Which Problems Are Solved

- When no auth was present on a smtp configuration, the `auth` field was
`nil` on the response while it should be `none`.
- Scopes were not properly retrieved from the database resulting in all
scopes being combined in one scope when retrieving the configuration.

# How the Problems Are Solved

- Set `auth` to `none` when no auth is configured
- Use `database.TextArray[string]` as type to get the scopes from the
database

# Additional Changes

# Additional Context

internal/api/grpc/admin/email_converters.go

@@ -108,6 +108,12 @@ func smtpToPb(config *query.SMTP) *settings_pb.EmailProvider_Smtp {
 		ret.Smtp.Auth = xoauth2
 	}
 
+	if config.XOAuth2Auth == nil && config.PlainAuth == nil {
+		ret.Smtp.Auth = &settings_pb.EmailProviderSMTP_None{
+			None: &settings_pb.SMTPNoAuth{},
+		}
+	}
+
 	return ret
 }
 

internal/api/grpc/admin/email_converters_test.go

@@ -407,6 +407,19 @@ func Test_smtpToPb(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "no auth must map to none",
+			args: args{
+				req: &query.SMTP{},
+			},
+			res: &settings_pb.EmailProvider_Smtp{
+				Smtp: &settings_pb.EmailProviderSMTP{
+					Auth: &settings_pb.EmailProviderSMTP_None{
+						None: &settings_pb.SMTPNoAuth{},
+					},
+				},
+			},
+		},
 		{
 			name: "plain auth must map to plain",
 			args: args{