Move ebpf code to its own package to avoid crash issues in Android (#1033)

* Move ebpf code to its own package to avoid crash issues in Android

Older versions of android crashes because of the bytecode files
Even when they aren't loaded as it was our case

* move c file to own folder

* fix lint

client/internal/wgproxy/ebpf/loader_test.go

@@ -0,0 +1,18 @@
+//go:build linux
+
+package ebpf
+
+import (
+	"testing"
+)
+
+func Test_newEBPF(t *testing.T) {
+	ebpf := NewEBPF()
+	err := ebpf.Load(1234, 51892)
+	defer func() {
+		_ = ebpf.Free()
+	}()
+	if err != nil {
+		t.Errorf("%s", err)
+	}
+}