Modify calculated channel value once total escrowed amounts are added to IBC

[nicolaslara]

Background

From the readme:

We have iterated on different strategies for calculating the channel value. Our preferred strategy is the following:

• For non-native tokens (ibc/...), the channel value should be the supply of those tokens in Osmosis
• For native tokens, the channel value should be the total amount of tokens in escrow across all ibc channels

The later ensures the limits are lower and represent the amount of native tokens that exist outside Osmosis. This is
beneficial as we assume the majority of native tokens exist on the native chain and the amount "normal" ibc transfers is
proportional to the tokens that have left the chain.

This strategy cannot be implemented at the moment because IBC does not track the amount of tokens in escrow across
all channels (github issue). Instead, we use the current supply on
Osmosis for all denoms (i.e.: treat native and non-native tokens the same way). Once that ticket is fixed, we will
update this strategy.

Suggested Design

• Modify channel value to use escrowed amounts
• Modify tests to match

Acceptance Criteria

Rate limiting uses escrowed amounts

[nicolaslara]

ref: cosmos/ibc-go#3019