Add 668 functions to 07-tendermint

[colin-axner]

In preparation for the additional functions to the client state interface, #668, add:

• VerifyHeader
• CheckForMisbehaviour
• UpdateStateOnMisbehaviour
• UpdateState

for tendermint client

Recommended splits:

PR 1

Rename Misbehaviour to DuplicateHeightHeader or some name like that (we can discuss on pr)

We decided to leave as Misbehaviour, see comment

PR 2

Rename checkValidity to VerifyHeader. Code may need to be modified to fulfill the expected functionality of VerifyHeader, including changing API or pulling in/removing code from the existing function.

Add a switch

switch header.(type) {
case NormalHeader:
   // verify one TM header
  
case DuplicateHeightHeader:
    // verify both TM headers
   
default:
    return error
}

Additional code may need to be added to the normal header or duplicate height header. Code should be deduplicated from CheckMisbehaviourAndUpdateState as well

PR 3

CheckForMisbehaviour should check for duplicate height misbehaviour and BFT Time violation misbehaviour. See existing code. Code should be deduplicated from CheckMisbehaviourAndUpdateState as well. Ensure duplicate header misbehaviour is checked by seeing if a consensus state already exists for that height

PR 4

UpdateStateOnMisbehaviour set client state in state to be frozen

Closed by: #1168

PR 5

Rename update to UpdateState. Should account for no-ops for duplicate headers. Do pruning logic within this function as well

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[colin-axner]

I will pickup PR 1

[seantking]

Edit: actually first I will start on -> #875

[seantking]

PR 2 & 3/4

[colin-axner]

Heyo. I can pickup pr 5