Add low level traits to retrieve name, symbol, decimals and allowance in pallet-assets (#9757)

* Add ERC20 compatible trait to retrieve name, symbol, decimals and allowance

* delegate instead of spender

* Remove erc20 trait and divide it into lower level traits

* add import

* approvals and metadata depend on fungibles

Co-authored-by: Shawn Tabrizi <[email protected]>