Parametrize the whitelisted tokens to allow for using it with L3s and Katana

[juanbono]

stark_compass_explorer/lib/starknet_explorer/token.ex

Line 5 in 2eac53e

@whitelisted_tokens_mainnet %{

We should make this configurable via a file or something and have the other ones as fallback if nothing is specified. To allow users to change the addresses of the whitelisted tokens. So it can be used with L3s and development sequencers like Katana.