refactor(api)!: remove unnecessary channel getter functions

[colin-axner]

Description

removes the extra getter functions that came with the exported.ChannelI interface. Unsure if someone would disagree with this proposed change so I split into a separate pr. I prefer the reduction of these functions as it keeps the code minimal and easier to grep

closes: #XXXX

Commit Message / Changelog Entry

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (9faaff5) 81.26% compared to head (023a8aa) 81.33%.
Report is 6 commits behind head on colin/rm-exported-channelI.

Additional details and impacted files

@@                      Coverage Diff                       @@
##           colin/rm-exported-channelI    #5705      +/-   ##
==============================================================
+ Coverage                       81.26%   81.33%   +0.07%     
==============================================================
  Files                             199      199              
  Lines                           15237    15216      -21     
==============================================================
- Hits                            12382    12376       -6     
+ Misses                           2389     2375      -14     
+ Partials                          466      465       -1     

Files	Coverage Δ
modules/apps/transfer/keeper/relay.go	90.94% <100.00%> (ø)
...odules/core/02-client/migrations/v7/solomachine.go	18.84% <ø> (+0.53%)	⬆️
modules/core/03-connection/keeper/verify.go	79.56% <100.00%> (+0.77%)	⬆️
modules/core/04-channel/types/channel.go	93.84% <ø> (+12.51%)	⬆️
modules/core/04-channel/types/codec.go	100.00% <ø> (ø)

[DimitrisJim]

pending removal of two calls in e2e that are causing em to fail, thanks for this clean-up! 🔥

[damiannolan]

Beautiful stuff!

Think we need to remove two calls to channel.GetConnectionHops() in e2e