Enforce Go style rules across codebase

Apply five style rules: convert iota string enums to typed
string constants, replace errors.As with errors.AsType,
merge three-group imports into two groups, fix multiline
parameter/argument formatting, and replace fmt.Sprintf URL
construction with net/url.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/bootstrap/saml.go

@@ -62,15 +62,19 @@ func GenerateSAMLCertificate() (cert string, key string, err error) {
 		return "", "", fmt.Errorf("create certificate: %w", err)
 	}
 
-	certPEM := pem.EncodeToMemory(&pem.Block{
-		Type:  "CERTIFICATE",
-		Bytes: certDER,
-	})
+	certPEM := pem.EncodeToMemory(
+		&pem.Block{
+			Type:  "CERTIFICATE",
+			Bytes: certDER,
+		},
+	)
 
-	keyPEM := pem.EncodeToMemory(&pem.Block{
-		Type:  "RSA PRIVATE KEY",
-		Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
-	})
+	keyPEM := pem.EncodeToMemory(
+		&pem.Block{
+			Type:  "RSA PRIVATE KEY",
+			Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
+		},
+	)
 
 	return string(certPEM), string(keyPEM), nil
 }