Add extractor test for go 1.16

ql/test/extractor-tests/go1.16/embed.expected

@@ -0,0 +1 @@
+| embeddedfile.go:9:5:9:5 | e |

ql/test/extractor-tests/go1.16/embed.ql

@@ -0,0 +1,5 @@
+import go
+
+from Variable v
+where exists(v.getDeclaration())
+select v

ql/test/extractor-tests/go1.16/embeddedfile.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	_ "embed"
+	"fmt"
+)
+
+//go:embed file
+var e string = "hi"
+
+func main() {
+	fmt.Println(e)
+	e = "why"
+	fmt.Println(e)
+}

ql/test/extractor-tests/go1.16/file

@@ -0,0 +1,2 @@
+file
+contents