Add anonymous func test helpers to packet tests

[damiannolan]

As suggested by @colin-axner in #4472

Introduce test helpers to reduce the amount of boilerplate code used in packet tests.

assertSuccess := func(commitment []byte, err error) {
    suite.Require().NoError(err)
    suite.Require().Nil(commitment)
    
    nextSequenceAck, found := suite.chainA.App.GetIBCKeeper().ChannelKeeper.GetNextSequenceAck(suite.chainA.GetContext(), packet.GetSourcePort(), packet.GetSourceChannel())
	
    suite.Require().True(found)
    suite.Require().Equal(uint64(1), nextSequenceAck, "sequence incremented for UNORDERED channel")
}

assertNoOp := func(commitment []byte, err error) {
    suite.Require().Error(err)
    suite.Require().ErrorIs(err, types.ErrNoOpMsg)
    suite.Require().Nil(commitment)
}

errorIs := func(expError error) func(commitment []byte, err error) {
    return  func(commitment []byte, err error) {
    suite.Require().Error(err)
    suite.Require().ErrorIs(err, types.ErrNoOpMsg)
    suite.Require().NotNil(commitment)
    }
}

// define test cases

expResult: assertSuccess
...

expResult: assertNoOp
...

expResult: errorIs(channeltypes.ErrChannelNotFound)

maybe in another followup if we like

Originally posted by @colin-axner in #4472 (comment)