abci++: add proto fields for enabling vote extensions (#8587)

This pull requests adds the protocol buffer field for the `ABCI.VoteExtensionsEnableHeight` parameter. This proto field is threaded throughout all of the relevant places where consensus params are used and referenced.

This PR also adds validation of the consensus param updates. Previous consensus param changes didn't depend on _previous_ versions of the params, so this change adds a method for validating against the old params as well.

closes: #8453

test/e2e/pkg/testnet.go

@@ -58,20 +58,21 @@ const (
 
 // Testnet represents a single testnet.
 type Testnet struct {
-	Name             string
-	File             string
-	Dir              string
-	IP               *net.IPNet
-	InitialHeight    int64
-	InitialState     map[string]string
-	Validators       map[*Node]int64
-	ValidatorUpdates map[int64]map[*Node]int64
-	Nodes            []*Node
-	KeyType          string
-	Evidence         int
-	LogLevel         string
-	TxSize           int
-	ABCIProtocol     string
+	Name                       string
+	File                       string
+	Dir                        string
+	IP                         *net.IPNet
+	InitialHeight              int64
+	InitialState               map[string]string
+	Validators                 map[*Node]int64
+	ValidatorUpdates           map[int64]map[*Node]int64
+	Nodes                      []*Node
+	KeyType                    string
+	Evidence                   int
+	VoteExtensionsEnableHeight int64
+	LogLevel                   string
+	TxSize                     int
+	ABCIProtocol               string
 }
 
 // Node represents a Tendermint node in a testnet.