Add test script for simple execution of all unit tests (#948)

* Resolves #947
* Simplify new/existing developer experience

Author: devin-petersohn

run-tests.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+arg=$arg
+
+if [ "$arg" == "" ]; then
+    arg="all"
+fi
+
+if [ "$arg" == "ray" ] || [ "$arg" == "all" ]; then
+    echo "Running Ray tests"
+    aws s3 cp  --no-sign-request s3://modin-testing/testmondata_ray .
+    mv testmondata_ray .testmondata
+    MODIN_ENGINE=ray pytest modin/pandas/test/
+fi
+if [ "$arg" == "python" ] || [ "$arg" == "all" ]; then
+    echo "Running Python tests"
+    aws s3 cp  --no-sign-request s3://modin-testing/testmondata_python .
+    mv testmondata_python .testmondata
+    MODIN_ENGINE=python pytest modin/pandas/test/
+fi
+if [ "$arg" == "dask" ] || [ "$arg" == "all" ]; then
+    echo "Running Dask tests"
+    aws s3 cp  --no-sign-request s3://modin-testing/testmondata_dask .
+    mv testmondata_dask .testmondata
+    MODIN_ENGINE=dask pytest modin/pandas/test/test_io.py
+fi
+if [ "$arg" == "pyarrow" ] || [ "$arg" == "all" ]; then
+    echo "Running Pyarrow tests"
+    aws s3 cp  --no-sign-request s3://modin-testing/testmondata_pyarrow .
+    mv testmondata_pyarrow .testmondata
+    MODIN_BACKEND=pyarrow MODIN_EXPERIMENTAL=1 pytest modin/pandas/test/test_io.py::test_from_csv
+fi