fix!: Charge gas for key length in gas meter (#10247)

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## Description

Closes: #10243 

Charge the per-byte fee for the key length as for the values in gas meter

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

store/gaskv/store.go

@@ -39,6 +39,7 @@ func (gs *Store) Get(key []byte) (value []byte) {
 	value = gs.parent.Get(key)
 
 	// TODO overflow-safe math?
+	gs.gasMeter.ConsumeGas(gs.gasConfig.ReadCostPerByte*types.Gas(len(key)), types.GasReadPerByteDesc)
 	gs.gasMeter.ConsumeGas(gs.gasConfig.ReadCostPerByte*types.Gas(len(value)), types.GasReadPerByteDesc)
 
 	return value
@@ -50,6 +51,7 @@ func (gs *Store) Set(key []byte, value []byte) {
 	types.AssertValidValue(value)
 	gs.gasMeter.ConsumeGas(gs.gasConfig.WriteCostFlat, types.GasWriteCostFlatDesc)
 	// TODO overflow-safe math?
+	gs.gasMeter.ConsumeGas(gs.gasConfig.WriteCostPerByte*types.Gas(len(key)), types.GasWritePerByteDesc)
 	gs.gasMeter.ConsumeGas(gs.gasConfig.WriteCostPerByte*types.Gas(len(value)), types.GasWritePerByteDesc)
 	gs.parent.Set(key, value)
 }
@@ -173,8 +175,10 @@ func (gi *gasIterator) Error() error {
 // based on the current value's length.
 func (gi *gasIterator) consumeSeekGas() {
 	if gi.Valid() {
+		key := gi.Key()
 		value := gi.Value()
 
+		gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostPerByte*types.Gas(len(key)), types.GasValuePerByteDesc)
 		gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostPerByte*types.Gas(len(value)), types.GasValuePerByteDesc)
 	}
 	gi.gasMeter.ConsumeGas(gi.gasConfig.IterNextCostFlat, types.GasIterNextCostFlatDesc)

store/gaskv/store_test.go

@@ -35,7 +35,7 @@ func TestGasKVStoreBasic(t *testing.T) {
 	require.Equal(t, valFmt(1), st.Get(keyFmt(1)))
 	st.Delete(keyFmt(1))
 	require.Empty(t, st.Get(keyFmt(1)), "Expected `key1` to be empty")
-	require.Equal(t, meter.GasConsumed(), types.Gas(6429))
+	require.Equal(t, meter.GasConsumed(), types.Gas(6858))
 }
 
 func TestGasKVStoreIterator(t *testing.T) {
@@ -74,16 +74,16 @@ func TestGasKVStoreIterator(t *testing.T) {
 	vb := iterator.Value()
 	require.Equal(t, vb, valFmt(2))
 	iterator.Next()
-	require.Equal(t, types.Gas(13377), meter.GasConsumed())
+	require.Equal(t, types.Gas(14565), meter.GasConsumed())
 	kc := iterator.Key()
 	require.Equal(t, kc, keyFmt(3))
 	vc := iterator.Value()
 	require.Equal(t, vc, valFmt(0))
 	iterator.Next()
-	require.Equal(t, types.Gas(13446), meter.GasConsumed())
+	require.Equal(t, types.Gas(14667), meter.GasConsumed())
 	require.False(t, iterator.Valid())
 	require.Panics(t, iterator.Next)
-	require.Equal(t, types.Gas(13476), meter.GasConsumed())
+	require.Equal(t, types.Gas(14697), meter.GasConsumed())
 	require.NoError(t, iterator.Error())
 
 	reverseIterator := st.ReverseIterator(nil, nil)
@@ -100,8 +100,7 @@ func TestGasKVStoreIterator(t *testing.T) {
 	reverseIterator.Next()
 	require.False(t, reverseIterator.Valid())
 	require.Panics(t, reverseIterator.Next)
-
-	require.Equal(t, types.Gas(13782), meter.GasConsumed())
+	require.Equal(t, types.Gas(15135), meter.GasConsumed())
 }
 
 func TestGasKVStoreOutOfGasSet(t *testing.T) {