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>

routers/api/v1/repo/release_attachment.go

@@ -6,7 +6,6 @@ package repo
 
 import (
 	"net/http"
-	"strings"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/context"
@@ -182,7 +181,7 @@ func CreateReleaseAttachment(ctx *context.APIContext) {
 	}
 
 	// Check if the filetype is allowed by the settings
-	err = upload.VerifyAllowedContentType(buf, strings.Split(setting.Attachment.AllowedTypes, ","))
+	err = upload.Verify(buf, header.Filename, setting.Repository.Release.AllowedTypes)
 	if err != nil {
 		ctx.Error(http.StatusBadRequest, "DetectContentType", err)
 		return