Migrate prices provider configuration for each network from Safe Client Gateway

[hectorgomezv]

Summary

The native coins and token prices are being retrieved from a third-party service (currently CoinGecko). The configuration data for each chain is hard-coded in the CGW code: https://github.com/safe-global/safe-client-gateway/blob/3df9a2423911460b9b5f5298dbb0d93ea2f05e1a/src/config/entities/configuration.ts#L31

We need to move this to the Safe Config Service to make it easier to change/add configurations without the need for a new release in the Client Gateway.

Requirements

• The configuration for each chain should include the nativeCoin and chainName fields that now live in the CGW configuration. As we already have a nativeCoin attribute in the Config Service's Chain entity, these attributes could be renamed in order to note they are CoinGecko-specific items.