[API] Add affected files of commits to commit struct (#14579)

* Add files affected by a commit to gitea API -- similar to github

* Add files affected by a commit to gitea API

* Fix stupid error

* Fix other stupid typo

* Generate swagger tmpl

* Comply with convert to git commit refacto

* update swagger docs

* extend test

* format code

* Update integrations/api_repo_git_commits_test.go

* Update modules/convert/git_commit.go

Co-authored-by: Laurent Cahour <laurent.cahour@dont-nod.com>
Co-authored-by: zeripath <art27@cantab.net>

templates/swagger/v1_json.tmpl

@@ -11821,6 +11821,13 @@
           "format": "date-time",
           "x-go-name": "Created"
         },
+        "files": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/CommitAffectedFiles"
+          },
+          "x-go-name": "Files"
+        },
         "html_url": {
           "type": "string",
           "x-go-name": "HTMLURL"
@@ -11843,6 +11850,17 @@
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
     },
+    "CommitAffectedFiles": {
+      "description": "CommitAffectedFiles store information about files affected by the commit",
+      "type": "object",
+      "properties": {
+        "filename": {
+          "type": "string",
+          "x-go-name": "Filename"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
     "CommitDateOptions": {
       "description": "CommitDateOptions store dates for GIT_AUTHOR_DATE and GIT_COMMITTER_DATE",
       "type": "object",