Improve calculation of the time since depositing on the Transactions list.

[michalinacienciala]

I'm not a fan of how the duration since depositing is displayed in the counter on the Transaction list. If a deposit was made at 12:00 and it's now 12:59 the counter shows the deposit was made 59 minutes ago. But if it's 13:01, the counter shows that the deposit was made 2 hours ago.

I think we should round the values down rather than up. @SorinQ agrees.

So the counter would be expected to work this way:

59 s
1 min
2 min
31 min
59 min
1 hour (60 - 119 min)
2 hours (120 - 179 min)
Etc.

I haven't checked yet how the counter works for withdrawals, but I assume it works the same and should be updated as well.

Tested in LL on the preview of #860.

[linear]

AENG-20 Improve calculation of the time since depositing on the Transactions list.