Improve texttest documentation

Specifically make it easier to test the Java version.
Added a test rig so you can use gradle to run the java version

Java/README.md

@@ -13,3 +13,7 @@ For e.g. 10 days:
 ```
 ./gradlew -q text --args 10
 ```
+
+## Run the TextTest approval test that comes with this project
+
+There are instructions in the [TextTest Readme](https://github.com/emilybache/GildedRose-Refactoring-Kata/blob/main/texttests/README.md) for setting up TextTest. What's unusual for the Java version is there are two executables listed in [config.gr](https://github.com/emilybache/GildedRose-Refactoring-Kata/blob/main/texttests/config.gr) for Java. One uses Gradle wrapped in a python script, the other relies on your CLASSPATH being set correctly in [environment.gr](https://github.com/emilybache/GildedRose-Refactoring-Kata/blob/main/texttests/environment.gr).

Java/src/main/java/com/gildedrose/GildedRose.java

@@ -59,4 +59,4 @@ class GildedRose {
             }
         }
     }
-}
+}

Java/texttest_rig.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+"""
+This script uses Gradle to execute the TexttestFixture.
+It is designed to be used by TextTest and specified in the file 'texttests/config.gr' in this repo.
+It is more convenient for TextTest to use since Gradle needs
+several arguments in addition to the one the TextTest fixture needs.
+"""
+import os
+import subprocess
+import sys
+
+args = " ".join(sys.argv[1:])
+TEXTTEST_HOME = os.environ.get("TEXTTEST_HOME", os.getcwd())
+subprocess.run(f"{TEXTTEST_HOME}/Java/gradlew -p {TEXTTEST_HOME}/Java -q text --args {args}", shell=True)