Use more_set_headers instead of add_headers throughout - esp http3

use

    more_set_headers 'Alt-Svc h3=":443"; ma=86400';
    more_set_headers 'QUIC-Status $http3';

instead of

    add_header Alt-Svc 'h3=":443"; ma=86400';
    add_header QUIC-Status $http3;

We will also need a scripts ticket, a worker to update all existing templates - separate ticket.

We also use add_header in a couple other contexts, which we will swap out

add_header "Access-Control-Allow-Origin" "*";

add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; connect-src 'self'; img-src 'self'; style-src 'self' 'unsafe-inline'; font-src 'self' data:;" always;

add_header Permissions-Policy "camera=(), fullscreen=(self), geolocation=(), magnetometer=(), microphone=(), midi=(), payment=(), sync-xhr=(), usb=(), speaker-selection=()";