[FR]: Source missing icons from coins repo on build

[smk762]

Is your feature request related to a problem? Please describe.
Currently there is potential for a coin to exist in the coins repo but have no icon in the desktop repo. There is also a duplication of tasks making a PR to both repos each time a new coin is added.

Describe your solution
During build, we already source the coins file and the coins_config.json file. An extra step to confirm icons for all coins in coins_config.json are present, and if not, to add them should resolve this.

Describe alternatives you've considered
Alternatively, we could setup a CI workflow to do this check periodically, and if new icons are detected, make a bot create a PR to include them here.