Show estimated duration in pending Staking/Unstaking tiles

[nkuba]

We want to display the estimated duration in the staking and unstaking tiles. We won't calculate the time remaining.

Discord thread

Staking

The duration for staking should be estimated based on the initial deposit amount, in the following ranges:

< 0.1 BTC               ~1 hour
>= 0.1 BTC  < 1 BTC     ~2 hours
>= 1 BTC                ~3 hours

Unstaking

For withdrawals, we will display 6 hours, regardless of the amount.

Designs

In this task, we additionally want to implement the UI changes proposed in Figma that affect the middle column components (pending transactions, position, transactions history).