make ibc_source_channel required for IBC transfers

[onur-ozkan]

For IBC transfers, if ibc_source_channel is not provided, we currently try to detect it automatically from https://github.com/cosmos/chain-registry. But this approach is risky and unreliable as the channels are often outdated, which could lead to a loss of funds (the fee part only). To improve safety and reliability we should remove this auto-detection logic and require users to specify ibc_source_channel manually and make them responsible for its correctness. This approach will allow users to rely on more reliable IBC channels by simply picking the most popular ones from sources like https://ibc.iobscan.io/channels.

[onur-ozkan]

These

komodo-defi-framework/mm2src/mm2_main/src/rpc/dispatcher/dispatcher.rs

Lines 209 to 210 in dfca6b7

	"ibc_chains" => handle_mmrpc(ctx, request, ibc_chains).await,
	"ibc_transfer_channels" => handle_mmrpc(ctx, request, ibc_transfer_channels).await,

2 RPCs should be removed as well.