Lnd: channeldb: open bbolt database with a timeout

[Roasbeef]

As is, when we open the database, we'll block indefinitely waiting to obtain the file lock on the database file. Instead, we should open the database with the timeout field specified. With a timeout value set, an error will be returned (which will shutdown lnd) if we're unable to open the database after a set duration.

[yyforyongyu]

I'm looking into this issue.

One question, to make this happen, we need to change this line in btcsuite/btcwallet/walletdb first?

[ErikEk]

I looked into the issue and I can't see any way around it.

[Roasbeef]

Should be able to proceed with this after https://github.com/btcsuite/btcwallet/pull/714 is merged.