Attachments: Add extension support, allow all types for releases (#12465)

* Attachments: Add extension support, allow all types for releases

- Add support for file extensions, matching the `accept` attribute of `<input type="file">`
- Add support for type wildcard mime types, e.g. `image/*`
- Create repository.release.ALLOWED_TYPES setting (default unrestricted)
- Change default for attachment.ALLOWED_TYPES to a list of extensions
- Split out POST /attachments into two endpoints for issue/pr and
  releases to prevent circumvention of allowed types check

Fixes: https://github.com/go-gitea/gitea/pull/10172
Fixes: https://github.com/go-gitea/gitea/issues/7266
Fixes: https://github.com/go-gitea/gitea/pull/12460
Ref: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers

* rename function

* extract GET routes out of RepoMustNotBeArchived

Co-authored-by: Lauris BH <lauris@nix.lv>

templates/repo/release/new.tmpl

@@ -49,10 +49,10 @@
 					<textarea name="content">{{.content}}</textarea>
 				</div>
 				{{if .IsAttachmentEnabled}}
-				<div class="field">
-					<div class="files"></div>
-					<div class="ui dropzone" id="dropzone" data-upload-url="{{AppSubUrl}}/attachments" data-accepts="{{.AttachmentAllowedTypes}}" data-max-file="{{.AttachmentMaxFiles}}" data-max-size="{{.AttachmentMaxSize}}" data-default-message="{{.i18n.Tr "dropzone.default_message"}}" data-invalid-input-type="{{.i18n.Tr "dropzone.invalid_input_type"}}" data-file-too-big="{{.i18n.Tr "dropzone.file_too_big"}}" data-remove-file="{{.i18n.Tr "dropzone.remove_file"}}"></div>
-				</div>
+					<div class="field">
+						<div class="files"></div>
+						{{template "repo/upload" .}}
+					</div>
 				{{end}}
 			</div>
 			<div class="ui container">