Add configuration to filter fee packets using recv fee as criteria

[ljoss17]

Closes: #1966

Description

This PR adds a new configuration to Hermes which allows users to relay only incentivized packets or incentivized packets which have at least a specific threshold as recv_fee.
This configuration can be done per channel.

New configuration

The new configuration per chain:

[chains.packet_filter.min_fees.'<channel>']
  recv    = [ { amount = <amount>, denom = '<denom>' } ]

The channel can be specified using regular expression matching, so to have a filter for all channels:

[chains.packet_filter.min_fees.'*']
  recv    = [ { amount = <amount>, denom = '<denom>' } ]

The denom is optional. If it is specified the packet must have a recv_fee with one of the specified denoms. For example this filter will only relay packets which have at least 20 utatom or 10 stake as recv_fee:

[chains.packet_filter.min_fees.'*']
  recv    = [ { amount = 20, denom = 'stake' }, { amount = 10, denom = 'uatom' } ]

And this will relay any packet which has at least 20 utatom, 10 stake or at least 50 of any token:

[chains.packet_filter.min_fees.'*']
  recv    = [  { amount = 20, denom = 'stake' }, { amount = 10, denom = 'uatom' }, { amount = 50} ]

recv_fee only

This solution only allows to filter SendPacket events if they do not have recv_fee or if the fee isn't high enough.
This choice has been made since allowing to filter acknowledgement and timeout would introduce much more overhead. And the if no acknowledgement or timeout is relayed, the fees will not be distributed and unescrowed.

Remarks

This configuration is experimental. Packet clearing is disabled for the channels which have a fee filter configured, and some SendPacket events might not be relayed if the IncentivizedPacket event is not in the same batch of events.

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PR author checklist:

• Added changelog entry, using unclog.
• Added tests: integration (for Hermes) or unit/mock tests (for modules).
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).
• Tagged one reviewer who will be the one responsible for shepherding this PR.

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[romac]

Great work @ljoss17! Overall it looks really good, left a bunch of minor requests and comments.