Check if the dropped file matches what the app expects/ implement match tables routine

[zaibquraishi]

We need to check to make sure the file they drop is an excel file with the first sheet being a table or "dataframe" with column headers that match the table that they say they are editing

Along with this we would have to make sure that the file they drop is even an excel file

In main.py we can put something like
return jsonify(user_error_msg="The file you dropped had such and such issue with it - please try again")

or something like that