[Feature request] Being able to import data into CanReg5, from spreadsheets

[AlexandreBonneau]

Is your feature request related to a problem? Please describe.
When you have multiple patient information to enter, you need to do this by hand.

Describe the solution you'd like
It would be great if it would be possible to import an .xls, .csv or .ods file to create multiple patients in one go.
Ideally and in order to simplify things, it would be great to have a way to first download an empty Excel template with the headers already set, so that the users would just have to add the relevant patient information at the right places.

Then an Import data... button would allow the users to select such Excel file, click Import and all the patients would then be created directly.

Later on, it would be great to be able to update the existing cases with that import feature as well, where you'd need to set the correct patient id in the Excel file so that CanReg would be able to identify which patient to update.
To make sure you would not delete fresh data, adding an 'updated_at' field in the database and in the Excel file would allow CanReg5 to check it the data to be imported is newer than the existing data in the database. If it is, import it, if not, ignore it and log it.

Describe alternatives you've considered
No alternatives

Additional context
This is needed when multiple new patients are created, or when laboratories are sending their results in batch.

Links
This issue is linked to #47.