PP-13145: Bind to localhost by default instead of 0.0.0.0

[jfharden]

WHAT

Bind to 127.0.0.1 by default, instead of 0.0.0.0

How

On master run:
npm run start:dev then when the app is running run, in another terminal run netstat, you'll see it's listening on all interfaces

$ netstat -anl | grep 3000
tcp46      0      0  *.3000                                        *.*                                           LISTEN

Then change to this branch, ryun npm run start:dev again and then netcat again, and you'll see it's listening on 127.0.0.1

$ netstat -anl | grep 3000
tcp4       0      0  127.0.0.1.3000                                *.*                                           LISTEN

Then kill the app, and to prove the env var works run BIND_HOST=0.0.0.0 npm run start:dev then a final netcat, and you'll see it's listening on all interfaces again

$ netstat -anl | grep 3000
tcp4       0      0  *.3000                                        *.*                                           LISTEN