install: answer every prompt from the environment, survive a closed stdin

Every interactive prompt takes a var_<app>_<name> override and treats a
closed stdin like Enter (`|| true`), so an install keeps going after the
console that started it is gone. Values the script cannot do without end
with exit 64 and name the variable to set. Validation loops stop asking
when nobody can answer instead of spinning on an empty read.

install/sqlserver2022-install.sh

@@ -46,7 +46,8 @@ echo 'export PATH="$PATH:/opt/mssql-tools18/bin"' >>~/.bash_profile
 source ~/.bash_profile
 msg_ok "Installed SQL Server Tools"
 
-read -r -p "${TAB3}Do you want to run the SQL server setup now? (Later is also possible) <y/N>" prompt
+prompt="${var_sqlserver2022_setup_now:-}"
+[[ -n "$prompt" ]] || read -r -p "${TAB3}Do you want to run the SQL server setup now? (Later is also possible) <y/N>" prompt || true
 if [[ "${prompt,,}" =~ ^(y|yes)$ ]]; then
   /opt/mssql/bin/mssql-conf setup
 else