Unify display of values of txs/assets/fees etc

There is a number of places where we show a rounded amount/value of a given tx/asset/fee etc.
In some of them we don't show any tooltip and in some we show tooltip with the amount that's the same as in the text we're hovering on.
In some places we show the rounded values without any indicator that the value got approximated and in some we use the ~, < or ... signs.

It would be good to unify our notation. We don't necessarily want to always display the amounts with the same precision - depending on the context we may want to round to two decimal places, or to six or eight. That's fine. But we should have a way of indicating that the shown amount got approximated. And in most places (although probably not all) where we show 0 or 2 decimal digits, it would be good to show more precise amount in a tooltip on hover.

We should think of a convention we want to use and fix all the places where it's not followed.

Some places we should think about:

1. Total account balance
2. Assets balances (on various views)
3. Values of txs in the Asset history or Activity view
4. Details of transactions
5. Values on Swap Assets view
6. NFTs values
7. Portfolio values

As part of this work we could also think whether we want to keep the current behavior regarding use of , and . in the displayed values. For values in USD we use . as a decimal separator (for example $1,051.63), whereas for other assets we use , as decimal separator (for example 23911,783). This may be a bit confusing, especially if both notations are used on the same view (like on Swap Assets view).