This method wraps LoadConfigFile to load all of the .tf and .tf.json files
in a given directory and then bundle them together into a Module object.
This function also deals with the distinction between primary and override
files, first appending together the primary files in lexicographic order
by filename, and then merging in override files in the same order.
The merging behavior is not fully implemented as of this commit, and so
will be expanded in future commits.
Much like TestParserLoadConfigFileSuccess, this is intended to be an
easy-to-maintain collection of bad examples to test different permutations
of our error handling.
As with TestParserLoadConfigFileSuccess, we should also have more specific
tests alongside this that check that the error outcome is what was
expected, since this test just accepts any error and may thus not be
testing what we think it is.
Martin Atkins