fix cargo clippy warnings

core/http/src/handlers/handler.rs

core/http/src/handling/request/form_utils.rs

core/http/src/handling/response/build_and_write.rs

core/http/src/handling/response/cookie_management/cookie.rs

core/http/src/handling/response/mod.rs

core/http/src/utils/url_utils/uri.rs

core/http/src/utils/urlencoded/datatypes.rs

core/http/src/utils/urlencoded/endecode.rs

core/http/src/utils/urlencoded/mod.rs

site/src/main.rs