Gitea public-only token bypass on bulk organization repository deletion

`DELETE /api/v1/orgs/{org}/repos` deletes all repositories of an organization, but it did not enforce the public-only restriction of access tokens: the route only checked that the organization itself was public. A public-only token of an owner of a public organization could therefore permanently delete the organization's private repositories, which such a token must not reach. Routes that require organization ownership now reject public-only tokens.