doctor/ethtool, ipn/ipnlocal: add ethtool bugreport check

Updates #11137

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Idbe862d80e428adb044249c47d9096b87f29d5d8

doctor/ethtool/ethtool.go

@@ -0,0 +1,23 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package ethtool provides a doctor.Check that prints diagnostic information
+// obtained from the 'ethtool' utility on the current system.
+package ethtool
+
+import (
+	"context"
+
+	"tailscale.com/types/logger"
+)
+
+// Check implements the doctor.Check interface.
+type Check struct{}
+
+func (Check) Name() string {
+	return "ethtool"
+}
+
+func (Check) Run(_ context.Context, logf logger.Logf) error {
+	return ethtoolImpl(logf)
+}