Feature request: add block height field for XMR/WOW wallet restore

[rottenwheel]

There's no option to add block height when going through wallet restore process, only date. If user's back-up does not have a date but instead block height per other wallet's notes, it could be tedious for users to try and guesstimate the block height of the certain date they have in their files when restoring wallet on Stack.

[sneurlax]

and using a raw block height would be easier as we currently use a hard-coded table relating dates to block heights in order to estimate the former to the latter.

[detherminal]

Completed in #1115