Add option for different report templates

[brandynlucca]

When running Survey.generate_reports, the current output intends to match the original EchoPro reports so there is backward compatibility for previous survey years. However, the option to produce files with Echopop naming schemes and designs should be enabled for future surveys. This could be in the form of Survey.generate_reports(legacy_mode: bool = True) or Survey.generate_reports(report_format: Literal["echopop", "echopro"] = "echopop").