Update IBC to use multi-chain configs

[jurevans]

See https://github.com/anoma/namada-interface/issues/140. which implements a new chain & extension configuration.

The IBC functionality in the interface needs to be updated and tested with the new multi-chain configurations.

• Accounts that are pulled from Keplr should be available for IBC transfers
• the user should be able to specify a channel and transfer tokens over IBC to an account on Keplr
• The token balances for Keplr accounts should appear in the interface

NOTE One caveat is that we may need to figure out the address for the supported tokens, i.e., what token address should we use for ATOM, OSMO, etc.?

[jurevans]

Closing as done