token::Amount may not be able to fully represent some wrapped token amounts

[james-chf]

On Namada, we have an Amount type which uses units of micros (10^-6).

namada/core/src/types/token.rs

Lines 32 to 34 in 76169dc

	pub struct Amount {
	micro: u64,
	}

Since we use u64 type for micros, the is maximum limit for how much a single Amount can hold is something like u64::MAX * 10^-6 which is roughly ~18.5bn full units. We use Amount type to represent amounts of native tokens on Namada as well as wrapped tokens from other chains. On Ethereum, ERC20 tokens can have supplies much larger than ~18.5bn e.g. SHIB. We want to be able to represent any wrapped token amounts in our Amount type.

Multiple possible solutions including changing our Amount type to support a higher supply (e.g. num256::Uint256 instead of u64), or using a different Amount type entirely for wrapped tokens.

[james-chf]

Have tagged this issue IBC as well as ethereum-bridge as I presume there are types of tokens that could come over IBC, that could be affected by this issue as well

[sug0]

Closed by #1282