[3743] Adds support for user search based on login or email (#7334)

* [3743] Adds support for user search based on login or email

* Use query parameter instead

* Use macaron Query() instead

docs/sources/http_api/user.md

@@ -69,6 +69,40 @@ parent = "http_api"
       "isGrafanaAdmin": true
     }
 
+## Get single user by Username(login) or Email
+
+    `GET /api/users/lookup`
+
+    **Parameter:** `loginOrEmail`
+
+    **Example Request using the email as option**:
+
+        GET /api/users/lookup?loginOrEmail=user@mygraf.com HTTP/1.1
+        Accept: application/json
+        Content-Type: application/json
+        Authorization: Bearer eyJrIjoiT0tTcG1pUlY2RnVKZTFVaDFsNFZXdE9ZWmNrMkZYbk
+
+    **Example Request using the username as option**:
+        GET /api/users/lookup?loginOrEmail=admin HTTP/1.1
+        Accept: application/json
+        Content-Type: application/json
+        Authorization: Bearer eyJrIjoiT0tTcG1pUlY2RnVKZTFVaDFsNFZXdE9ZWmNrMkZYbk
+
+    **Example Response**:
+
+        HTTP/1.1 200
+        Content-Type: application/json
+
+        {
+          "email": "user@mygraf.com"
+          "name": "admin",
+          "login": "admin",
+          "theme": "light",
+          "orgId": 1,
+          "isGrafanaAdmin": true
+        }
+
+
 ## User Update
 
 `PUT /api/users/:id`