x/tools: modernize interface{} -> any

Produced with a patched version of modernize containing only
the efaceany pass:

$ go run ./gopls/internal/analysis/modernize/cmd/modernize/main.go -test -fix ./... ./gopls/...

This is very safe and forms the bulk of the modernize diff,
isolating the other changes for ease of review.

Change-Id: Iec9352bac5a639a5c03368427531c7842c6e9ad0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/650759
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>

internal/jsonrpc2/wire.go

@@ -45,7 +45,7 @@ const wireVersion = "2.0"
 // We can decode this and then work out which it is.
 type wireCombined struct {
 	VersionTag string          `json:"jsonrpc"`
-	ID         interface{}     `json:"id,omitempty"`
+	ID         any             `json:"id,omitempty"`
 	Method     string          `json:"method,omitempty"`
 	Params     json.RawMessage `json:"params,omitempty"`
 	Result     json.RawMessage `json:"result,omitempty"`