Remove Route method in favour of Verify(Non)Membership on client keeper

[damiannolan]

food for thought.. I wonder if we should rather be exposing VerifyMembership and VerifyNonMembership as client keeper methods now since in other places in 03-connection/04-channel where we did clientState look ups to do things like status, latest height, timestamp at height etc, we're now using client keeper methods which abstract away the router lookups.

I feel like this might be more in line with 02-client's purpose as a router in general. If dependent modules need to do custom things there is a GetRouter method exposed in 02-client

Interested to hear what others think 🤔

Originally posted by @damiannolan in #6013 (comment)

[colin-axner]

Sounds like a good idea to me 👍

[crodriguezvega]

I believe this is what needs to be done, please correct me if I am wrong:

• Remove Route function from ClientKeeper interface.
• Add functions to ClientKeeper interface:

VerifyMembership(
  ctx sdk.Context,
  clientID string,
  height Height,
  delayTimePeriod uint64,
  delayBlockPeriod uint64,
  proof []byte,
  path Path,
  value []byte,
) error
VerifyNonMembership(
  ctx sdk.Context,
  clientID string,
  height Height,
  delayTimePeriod uint64,
  delayBlockPeriod uint64,
  proof []byte,
  path Path,
) error

• Implement the above functions. Get the client module like this (this could be extracted to a helper unexported function, since it will be repeated in a few places), and then call the corresponding function.
• Use the functions implemented above in the Verify... functions of 03-connection.