config: rename noencryptwallet to noseedbackup
config: rename noencryptwallet to noseedbackup

This commit renames the confusing noencryptwallet
flag to noseedbackup, since this highlights the more
crucial information of the flags behavior to the user.
The description has also been capitalized to urge
the user think twice about what they're doing.

aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd,aakselrod/lnd