Currency pictograms and country flags

Each currency should have clear symbols/graphics attached:
* Pictogram, i.e. small text-like symbols denoting the currency
* Flag of the country which uses the currency

If pictograms can be provided by unicode, then we can use it. But what I've found [here](https://www.xe.com/symbols/) doesn't make a lot of sense to me. E.g. Turkish Lyra is correct: `₺` but Kazakhstan Tenge is wrong: `лв`

No files, tests, or entry points are identified. Start by locating where currencies are represented and displayed, then determine how symbol and country-flag data is sourced; done means each supported currency has a correct pictogram and associated country flag, using Unicode where appropriate.

Written by the indexing model from the issue text.