build: Use only meson for squeekboard

This breaks autoconf. The only resulting binary is the squeekboard GUI. It still needs the autotools-built eekboard client in order to do anything useful. That one needs to be built using a different branch, making this a WIP.
1 job for squeekboard_binary in 1 minute and 23 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #10954
librem5
build_automake

00:01:23