Contents API should return 404 on not exist (#10323)

* Return 404 on not exist

* swagger update and use git.IsErrNotExist

* Handle delete too

* Handle delete too x2

* Fix pr 10323 (#3)

* fix TESTS

* leafe a note for fututre

* placate golangci-lint

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Update integrations/api_repo_file_delete_test.go

Co-Authored-By: 6543 <6543@obermui.de>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

templates/swagger/v1_json.tmpl

@@ -2638,6 +2638,9 @@
         "responses": {
           "200": {
             "$ref": "#/responses/ContentsListResponse"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
           }
         }
       }
@@ -2684,6 +2687,9 @@
         "responses": {
           "200": {
             "$ref": "#/responses/ContentsResponse"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
           }
         }
       },
@@ -2831,6 +2837,15 @@
         "responses": {
           "200": {
             "$ref": "#/responses/FileDeleteResponse"
+          },
+          "400": {
+            "$ref": "#/responses/error"
+          },
+          "403": {
+            "$ref": "#/responses/error"
+          },
+          "404": {
+            "$ref": "#/responses/error"
           }
         }
       }