Render WebP attachments as image by default

This adds the .webp file extension to the list of safe image extensions
in the file type detection. It allows webp-images to be uploaded to
issues and comments which then get embeded as images instead of
attachments (see [gitlab-org/gitlab#296600](3)). It also allows uploading
of designs in the webp format. WebP is supported in all browsers that
GitLab supports except Safari <= macOS 10
(see [caniuse][1], [suppported browsers][2]).

[1]: https://caniuse.com/webp
[2]: https://docs.gitlab.com/ee/install/requirements.html#supported-web-browsers
[3]: https://gitlab.com/gitlab-org/gitlab/-/issues/296600

changelogs/unreleased/add-webp-to-file-type-detection.yml

+---
+title: Render WebP attachments as image by default
+merge_request: 51088
+author: Kev @KevSlashNull
+type: changed

doc/user/project/issues/design_management.md

@@ -46,7 +46,7 @@ If the requirements are not met, the **Designs** tab displays a message to the u
 ## Supported files
 
 Files uploaded must have a file extension of either `png`, `jpg`, `jpeg`,
-`gif`, `bmp`, `tiff`, `ico`, or `svg`.
+`gif`, `bmp`, `tiff`, `ico`, `webp`, or `svg`.
 
 Support for [PDF](https://gitlab.com/gitlab-org/gitlab/issues/32811) is planned for a future release.
 

lib/gitlab/file_type_detection.rb

@@ -19,7 +19,7 @@
 # `Content-Type` and `Content-Disposition` to the one we get from the detection.
 module Gitlab
   module FileTypeDetection
-    SAFE_IMAGE_EXT = %w[png jpg jpeg gif bmp tiff ico].freeze
+    SAFE_IMAGE_EXT = %w[png jpg jpeg gif bmp tiff ico webp].freeze
     SAFE_IMAGE_FOR_SCALING_EXT = %w[png jpg jpeg].freeze
 
     PDF_EXT = 'pdf'

spec/models/group_spec.rb

@@ -410,7 +410,7 @@ RSpec.describe Group do
 
     it "is false if avatar is html page" do
       group.update_attribute(:avatar, 'uploads/avatar.html')
-      expect(group.avatar_type).to eq(["file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico"])
+      expect(group.avatar_type).to eq(["file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico, webp"])
     end
   end
 

spec/models/project_spec.rb

@@ -1256,7 +1256,7 @@ RSpec.describe Project, factory_default: :keep do
 
     it 'is false if avatar is html page' do
       project.update_attribute(:avatar, 'uploads/avatar.html')
-      expect(project.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico'])
+      expect(project.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico, webp'])
     end
   end
 

spec/models/user_spec.rb

@@ -2477,7 +2477,7 @@ RSpec.describe User do
     it 'is false if avatar is html page' do
       user.update_attribute(:avatar, 'uploads/avatar.html')
 
-      expect(user.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico'])
+      expect(user.avatar_type).to eq(['file format is not supported. Please try one of the following supported formats: png, jpg, jpeg, gif, bmp, tiff, ico, webp'])
     end
   end