chore: make EscrowPacketFee private

[damiannolan]

Description

• Modified EscrowPacketFee to be unexported - escrowPacketFee
• Moved IsFeeEnabled checks to msg_server.go
• Removed all references to EscrowPacketFee in tests. Explicitly set fees in escrow and send coins to module account
• Updated PayPacketFee and PayPacketFeeAsync tests to accommodate unexported escrowPacketFee

closes: #1059

---

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[seantking]

Annoying chore task. Thanks for looking into it! I'm mostly concerned about leaving out the checks we have in the removed EscrowPacketFee test.

I'm fine with leaving EscrowPacketFee public if it's too much work/not feasible.

[colin-axner]

ACK pending the additional testing checks in msg_server_test.go as requested by @seantking

Great work! Not a fun pr to take on, but I'm a fan of the code improvement. Makes our tests slightly less nice, but I like having a clear entry point exposed to this functionality. Will prevent external developers from making mistakes. I feel pretty confident that someone would try to directly call EscrowPacketFee instead of sending a PayPacketFee message - thus bypassing the checks we have in place

[codecov-commenter]

Codecov Report

Merging #1252 (eb2120b) into main (e59a6d2) will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1252      +/-   ##
==========================================
+ Coverage   80.15%   80.23%   +0.08%     
==========================================
  Files         166      166              
  Lines       11943    11937       -6     
==========================================
+ Hits         9573     9578       +5     
+ Misses       1912     1905       -7     
+ Partials      458      454       -4     

Impacted Files	Coverage Δ
modules/apps/29-fee/keeper/escrow.go	90.74% <100.00%> (+2.45%)	⬆️
modules/apps/29-fee/keeper/msg_server.go	93.33% <100.00%> (+15.28%)	⬆️
modules/apps/transfer/keeper/keeper.go	94.20% <0.00%> (-0.17%)	⬇️
...7-interchain-accounts/controller/keeper/account.go	72.72% <0.00%> (ø)
modules/apps/transfer/keeper/genesis.go	89.47% <0.00%> (+6.14%)	⬆️

[seantking]

Approved but I noticed we don't check for the stored fees in escrow anymore -> https://github.com/cosmos/ibc-go/pull/1252/files#r850491652

Is this something we want to keep? I get it's somewhat redundant but may be a good safety check. I think it's worth adding.