feat(handlers): CRUDL support for static Username-Password-Domain credentials

internal/proto/controller/api/resources/credentials/v1/credential.proto

@@ -77,6 +77,11 @@ message Credential {
       (custom_options.v1.generate_sdk_option) = true,
       (custom_options.v1.subtype) = "json"
     ];
+    UsernamePasswordDomainAttributes username_password_domain_attributes = 104 [
+      (google.api.field_visibility).restriction = "INTERNAL",
+      (custom_options.v1.generate_sdk_option) = true,
+      (custom_options.v1.subtype) = "username_password_domain"
+    ];
   }
 
   // Output only. The available actions on this resource for this user.
@@ -114,6 +119,44 @@ message UsernamePasswordAttributes {
   ]; // @gotags: `class:"public"`
 }
 
+message UsernamePasswordDomainAttributes {
+  // The username associated with the credential.
+  google.protobuf.StringValue username = 10 [
+    (custom_options.v1.generate_sdk_option) = true,
+    (custom_options.v1.mask_mapping) = {
+      this: "attributes.username"
+      that: "Username"
+    }
+  ]; // @gotags: `class:"public"`
+
+  // Input only. The password associated with the credential.
+  google.protobuf.StringValue password = 20 [
+    json_name = "password",
+    (custom_options.v1.generate_sdk_option) = true,
+    (custom_options.v1.mask_mapping) = {
+      this: "attributes.password"
+      that: "Password"
+    }
+  ]; // @gotags: `class:"secret"`
+
+  // Output only. The hmac value of the password.
+  string password_hmac = 30 [
+    json_name = "password_hmac",
+    (custom_options.v1.mask_mapping) = {
+      this: "attributes.password_hmac"
+      that: "PasswordHmac"
+    }
+  ]; // @gotags: `class:"public"`
+
+  google.protobuf.StringValue domain = 40 [
+    (custom_options.v1.generate_sdk_option) = true,
+    (custom_options.v1.mask_mapping) = {
+      this: "attributes.domain"
+      that: "Domain"
+    }
+  ]; // @gotags: `class:"public"`
+}
+
 // The attributes of a SshPrivateKey Credential.
 message SshPrivateKeyAttributes {
   // The username associated with the credential.