Add way to customize host and port for `build-and-serve.sh`

[adamscott]

With this PR, we can customize the host and port for build-and-serve.sh utility script.

# Sets the host to localhost instead of the default 0.0.0.0
SERVER_HOST=localhost ./build-and-serve.sh
# Sets the port to 4001 instead of the default 4000
SERVER_PORT=4001 ./build-and-serve.sh
# Sets both values
SERVER_HOST=localhost SERVER_PORT=4001 ./build-and-serve.h

[coppolaemilio]

"${THANKS:-0.0.0.0}"