Change ERC-20 rows to cells and restructure tableview

[ricburton]

Right now the ERC-20s are in this expanding single cell which I think will lead to issues down the road.

Could we look at something like this to make the whole system cleaner?

https://github.com/younatics/ExpandableCell

I have looked through lots of libraries and this looks well maintained, updated for Swift 5, and a nice base for us to work off.

@einsteinx2, @borwahs & @jamierumbelow curious to hear what you think.

[einsteinx2]

Ahh I see, so this essentially adds the extra rows in. Not sure how it would work though with the current design where the whole expanding cell has a border or looks like singular cell (unless I'm out of date on the current design which is totally possible). We might be able to hack that in, but if we switch to this, are you ok with the design looking like separate cells rather than one big cell?