Update benchmark tests to run against generic workload, data loading with scale factor, +more

This change updates the run-benchmark script to enable it to target one or more
workloads. Now benchmarks can be run like:

./run-benchmark --workloads=hive-benchmark,tpch

We lookup the workload in the workloads directory, then read the associated
query .test files and start executing them.

To ensure the queries are not duplicated between benchmark and query tests, I
moved all existing queries (under fe/src/test/resources/* to the workloads
directory. You do NOT need to look through all the .test files, I've just moved
them. The one new file is the 'hive-benchmark.test' which contains the hive
benchmark queries.

Also added support for generating schema for different scale factors as well as
executing against these scale factors. For example, let's say we have a dataset
with a scale factor called "SF1". We would first generate the schema using:

./generate_schema_statements --workload=<workload> --scale_factor="SF3"
This will create tables with a unique names from the other scale factors.

Run the generated .sql file to load the data. Alternatively, the data can loaded
by running a new python script:
./bin/load-data.py -w <workload1>,<workload2> -e <exploration strategy> -s [scale factor]
For example: load-data.sh -w tpch -e core -s SF3

Then run against this:
./run-benchmark --workloads=<workload> --scale_factor=SF3

This changeset also includes a few other minor tweaks to some of the test
scripts.

Change-Id: Ife8a8d91567d75c9612be37bec96c1e7780f50d6

testdata/workloads/functional-query/queries/QueryTest/empty.test

@@ -0,0 +1,18 @@
+# testtbl is empty
+select * from testtbl$TABLE
+---- TYPES
+bigint, string, int
+---- RESULTS
+====
+# month ends at 12
+select int_col from alltypessmall$TABLE where month > 100
+---- TYPES
+int
+---- RESULTS
+====
+# Empty partitioned table test
+select field from emptytable
+---- TYPES
+string
+---- RESULTS
+====