simlify core symbol config

[vadim-di]

No description provided.

[maoueh]

Two things.

• You made some changes to CLI flag, those should be made in a separate pull request for proper discussion.
• Your simplification removes all the previous code that was making an API call to infer the proper symbol based on the API endpoint hit. All this logic must still apply.

What you use case for this? Complete off-line usage?

[vadim-di]

I've found its not actually use flag --core-symbol trying to fetch it from chain. And the decimal point do not change if I decide to transfer other tokens like BNT. You can drop CLI changes, but do something with symbol and decimals.