Added lab experiment to check H2 MVStore perf

tools_scripts/lab/squareTapeTest.groovy

@@ -0,0 +1,16 @@
+@Grab(group='com.squareup', module='tape', version='1.2.3')
+import com.squareup.tape.QueueFile
+
+byte[] content = UUID.randomUUID().toString().bytes//[0x0C, 0x0A, 0x0F, 0x0E, 0x0B, 0x0A, 0x0B, 0x0E] as byte[]
+
+numMessages = 10000
+def file = File.createTempFile("tape", ".bin")
+println "Created tmp file"
+QueueFile queue = new QueueFile(file)
+println "Created queue and starting"
+long start = System.currentTimeMillis()
+(1..numMessages).each {
+    queue.add(content)
+}
+long stop = System.currentTimeMillis()
+println "Wrote ${numMessages*content.length} bytes in ${stop-start} ms"