Add SQL tracing via DENDRITE_TRACE_SQL (#968)

* Add SQL tracing via DENDRITE_TRACE_SQL

Add this to `internal/sqlutil` in preparation for #897

* Not entirely

internal/sqlutil/trace_driver_wasm.go

@@ -0,0 +1,33 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build wasm
+
+package sqlutil
+
+import (
+	"database/sql"
+
+	sqlitejs "github.com/matrix-org/go-sqlite3-js"
+	"github.com/ngrok/sqlmw"
+)
+
+func registerDrivers() {
+	if !tracingEnabled {
+		return
+	}
+	// install the wrapped drivers
+	sql.Register("sqlite3_js-trace", sqlmw.Driver(&sqlitejs.SqliteJsDriver{}, new(traceInterceptor)))
+
+}