Experiment with addons

Addons allow to execute external programs in some context inside
docspell. Currently it is possible to run them after processing files.
Addons are provided by URLs to zip files.

modules/joexapi/src/main/resources/joex-openapi.yml

@@ -122,8 +122,45 @@ paths:
               schema:
                 $ref: "#/components/schemas/BasicResult"
 
+  /addon/config:
+    get:
+      operationId: "v1-addon-config-get"
+      tags: [ Addons ]
+      summary: What is supported running addons
+      description: |
+        Return what this joex supports when executing addons.
+      responses:
+        422:
+          description: BadRequest
+        200:
+          description: Ok
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AddonSupport"
+
 components:
   schemas:
+    AddonSupport:
+      description: |
+        How this joex supports executing addons.
+      required:
+        - nodeId
+        - runners
+      properties:
+        nodeId:
+          type: string
+          format: ident
+        runners:
+          type: array
+          items:
+            type: string
+            format: addon-runner-type
+            enum:
+              - nix-flake
+              - docker
+              - trivial
+
     JobAndLog:
       description: |
         Some more details about the job.