Replace bash JavaTest.sh with mvn test (#7500)

* Start of mvn-ification of the test

* move to right locations

* Update the IO done in the test to read from resources / write to temp folders

* Add github workflow attempt to mvn test it instead of JavaTest.sh

* Pin the Kotlin benchmark's symlink for /java to the right location

* Inline equality assertions and format JavaTest.java

* fix android gradle source directory

Co-authored-by: Derek Bailey <derekbailey@google.com>

java/src/test/java/DictionaryLookup

@@ -0,0 +1 @@
+../../../../tests/DictionaryLookup

java/src/test/java/MyGame

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+../../../../tests/MyGame

java/src/test/java/NamespaceA

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+../../../../tests/namespace_test/NamespaceA

java/src/test/java/NamespaceC

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+../../../../tests/namespace_test/NamespaceC

java/src/test/java/optional_scalars

@@ -0,0 +1 @@
+../../../../tests/optional_scalars

java/src/test/java/union_vector

@@ -0,0 +1 @@
+../../../../tests/union_vector