Verifying correctness of the downloaded structure

Part of the motivation for this tool is to ensure we always structure directories containing EML files according to some standardised definition. EmlGet should verify whether obtained files from specific election types conform to such a definition, preferably through unit tests.

Once a definition is made available, it may also be wise to inform the user of the structure in which their files were downloaded.

Start by reviewing EmlGet's download and directory-structuring entry point, along with the existing unit-test setup. The issue does not provide the standardized definitions, so first clarify the expected structure for each election type; done means downloaded EML files are checked against those definitions and any user-facing structure information has an agreed scope.

Written by the indexing model from the issue text.