Make launching containers non-interactive for xud-ui

Current state of xud-docker requires user input after starting the script to launch containers.

In order to provide smooth user experience for UI projects we'll need non-interactive mode.

bash xud.sh --non-interactive --mainnet should:

1. Start all containers for mainnet
2. Setup temporary backup directory
3. Initialize the wallet with default password xud-docker (since we're using aezeed we can change the password later via API call)

[reliveyy]

@ERKarl I suggest we use command-line options to disable interactive questions.

• --network simnet disables interactive networking choosing
• --wallet-password disables interactive password setting during wallet creation
• --backup-dir disables interactive backup folder setting and create/restore selection (if no --restore-dir then create)
• --restore-dir disables interactive restore folder setting and create/restore selection (if having --restore-dir then restore)

E.g.

# Example 1 (create)
bash xud.sh --network testnet --backup-dir ~/.xud-docker/testnet/backup --wallet-password 'secret'

# Example 2 (restore)
bash xud.sh --network mainnet --backup-dir /new/backup/location --wallet-password 'unlock' \
--restore-dir /old/xud-docker/mainnet 

# Example 3 (discard --wallet-password in command-line)
source vault.env # contains XUD_DOCKER_WALLET_PASSWORD='deepsecret'
bash xud.sh --network mainnet --backup-dir ... 

P.S. If using non-interactive create then seed.txt will be saved under network-dir.

[reliveyy]

--network is added in #750

@reliveyy how would this work for Windows?

Could we provide these options as environment variables?

docker run --env ENV_CONFIG="..."

@reliveyy how would this work for Windows?

Making this work on Windows is probably out of context of this issue though.