Make Jpegli standalone, remove most part of libjxl code #18

Job	Run time
.deb packages / ubuntu:22.04	1m 13s
.deb packages / ubuntu:20.04	1m 6s
.deb packages / debian:bullseye	1m 12s
.deb packages / debian:bookworm	1m 3s
.deb packages / debian:trixie	1m 8s
.deb packages / debian:sid	59s
Release linux x86_64 static	3m 3s
Windows Build (vcpkg / x86-windows-static)	6m 10s
Windows Build (vcpkg / x64-windows-static)	6m 32s
Windows Build (vcpkg / x86-windows)	4m 36s
Windows Build (vcpkg / x64-windows)	4m 14s
	31m 16s

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