add flag to buy/sell commands for order auto-placement after connext collateralization

[raladev]

Current behavior (after #1885 PR):

At first u need to ask for collateral and anly after that u will be able to place order

simnet > buy 0.5 ETH/BTC 0.1 1
2 UNKNOWN: channel collateralization in progress, please try again in ~1 minute
simnet > buy 0.5 ETH/BTC 0.1 1
2 UNKNOWN: channel collateralization in progress, please try again in ~1 minute
simnet > buy 0.5 ETH/BTC 0.1 1
2 UNKNOWN: channel collateralization in progress, please try again in ~1 minute

Suggestion:

1. add flag to buy/sell command to place order immediately after collateralization;
2. default value for flag is false (do not place order automatically).

Problems:

1. collateralization may took significant time - ~10-60 min and u cant cancel placing if u want