feat(devfile): Update devfile 2.1 schema to the revision used by DevWorkspace Operator

(attributes being available at the root level)
https://github.com/devfile/devworkspace-operator/issues/406

Change-Id: I5d8ee432aeaf62a9453cc23d443394776eb633ee
Signed-off-by: Florent Benoit <fbenoit@redhat.com>

wsmaster/che-core-api-workspace/src/main/resources/schema/2.1.0-alpha/devfile.json

@@ -6,6 +6,11 @@
     "schemaVersion"
   ],
   "properties": {
+    "attributes": {
+      "description": "Map of implementation-dependant free-form YAML attributes.",
+      "type": "object",
+      "additionalProperties": true
+    },
     "commands": {
       "description": "Predefined, ready-to-use, devworkspace-related commands",
       "type": "array",
@@ -632,7 +637,7 @@
       "type": "object",
       "properties": {
         "attributes": {
-          "description": "Map of implementation-dependant free-form YAML attributes.",
+          "description": "Map of implementation-dependant free-form YAML attributes. Deprecated, use the top-level attributes field instead.",
           "type": "object",
           "additionalProperties": true
         },
@@ -704,6 +709,11 @@
         }
       ],
       "properties": {
+        "attributes": {
+          "description": "Overrides of attributes encapsulated in a parent devfile. Overriding is done according to K8S strategic merge patch standard rules.",
+          "type": "object",
+          "additionalProperties": true
+        },
         "commands": {
           "description": "Overrides of commands encapsulated in a parent devfile or a plugin. Overriding is done according to K8S strategic merge patch standard rules.",
           "type": "array",
@@ -1524,6 +1534,13 @@
         "uri": {
           "description": "Uri of a Devfile yaml file",
           "type": "string"
+        },
+        "variables": {
+          "description": "Overrides of variables encapsulated in a parent devfile. Overriding is done according to K8S strategic merge patch standard rules.",
+          "type": "object",
+          "additionalProperties": {
+            "type": "string"
+          }
         }
       },
       "additionalProperties": false
@@ -1783,6 +1800,13 @@
         },
         "additionalProperties": false
       }
+    },
+    "variables": {
+      "description": "Map of key-value variables used for string replacement in the devfile. Values can can be referenced via {{variable-key}} to replace the corresponding value in string fields in the devfile. Replacement cannot be used for\n\n - schemaVersion, metadata, parent source  - element identifiers, e.g. command id, component name, endpoint name, project name  - references to identifiers, e.g. in events, a command's component, container's volume mount name  - string enums, e.g. command group kind, endpoint exposure",
+      "type": "object",
+      "additionalProperties": {
+        "type": "string"
+      }
     }
   },
   "additionalProperties": false

wsmaster/che-core-api-workspace/src/test/resources/devfile/schema_test/devfile/devfile_v2-1-0-alpha_simple-devfile.yaml

@@ -13,6 +13,8 @@
 schemaVersion: 2.1.0-alpha
 metadata:
   name: spring-petclinic
+attributes:
+  example: foo
 components:
   - name: maven
     container: