lighttpd: update to upstream 1.4.61

lighttpd: update to upstream 1.4.61

imports Makefile and patches from openwrt: https://github.com/openwrt/packages/pull/16798 and https://github.com/openwrt/packages/pull/17011

This merge request changes the lighttpd package to match upstream OpenWRT and to use the Nettle library for hashing crypto functions (e.g. SHA256), separate from the lighttpd TLS modules. The lighttpd TLS module lighttpd-mod-openssl is still the default, but lighttpd modules for alternative TLS libraries are available, if configured during the build.

Note: this merge request preserves Turris-specific lighttpd Makefile define Package/lighttpd/postinst rule and Turris-specific use of /etc/lighttpd/modules.d/ since #474 (closed) has been pushed out to %Turris OS 6.0