Allow permissionless whitelisting of ERC20s

[lumtis]

This task group issues and considerations that are necessary in the protocol to allow permissionless whitelisting of ERC20.

Basically the user can send the MsgWhitelistERC20 to add support to a new ERC20.
Eventually we can consider a precompile contract allowing to whitelist a token solely through EVM interactions.

Considerations:

• Optimize indexing of ZRC20 with the idea in mind that adding new asset could be spammed
• Prevent adding two same ERC20 (current possible)
• Like Allow to create a ZetaChain native ZRC20 that can be used on any chain #2740 consider aspect that could add utility to the ZETA token. Example: having to stake a certain amount of ZETA token to allow whitelisting a new ERC20
• Make deeper research of security implication of permissionless whitelisting

Tasks

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1. Allow to retrieve directly in store foreign coin from ERC20 asset #1139
   m:fungible security +2
2. ZRC20 Liquidity Caps should have a default value #2521
   bug +1