Improved `start` CLI script

[appy-one]

This adds more configuration options to the start script, which is now available from the CLI with npx acebase-server start DBNAME=mydb HOST=localhost PORT=3000

Documentation:

Use environment variables or pass arguments to this script to start an AceBase server
instance from the command-line.

Command-line arguments format:
`npx acebase-server start DBNAME=mydb HOST=localhost PORT=3000`
You can use all variables mentioned below (without 'ACEBASE_' prefix)

All environment variables MUST be prefixed with 'ACEBASE_' (except for PORT if ACEBASE_PORT is not specified).
Currently available environment variables:

# File and network settings:
ACEBASE_DBNAME='mydb'
ACEBASE_DBPATH='.'
ACEBASE_HOST='localhost'
ACEBASE_PORT='3000'
ACEBASE_ROOT_PATH=''

# Transaction logging settings:
ACEBASE_TXLOG='true'
ACEBASE_TXDAYS='30'

# Auth settings:
ACEBASE_AUTH='true'
ACEBASE_AUTH_USER_SIGNUP='true'
ACEBASE_AUTH_DEFAULT_ACCESS_RULE='deny'
ACEBASE_AUTH_DEFAULT_ADMIN_PASSWORD=''
ACEBASE_AUTH_NEW_USER_RATE_LIMIT='0'
ACEBASE_AUTH_SEPARATE_DB='false'
ACEBASE_AUTH_TOKENS_EXPIRE='0'

# IPC configuration for single machine clusters
ACEBASE_IPC='socket'

# IPC configuration for multiple machine clusters (Make sure there is ONLY ONE 'master' instance)
ACEBASE_IPC_PORT='9163'
ACEBASE_IPC_HOST='ipc.example.com'
ACEBASE_IPC_ROLE='master'
ACEBASE_IPC_SSL='true'
ACEBASE_IPC_TOKEN='secret'