Feature: Inference for Excel file extensions

[talagluck]

Description

Currently, for CSV files, both of these will work

SELECT * FROM read_csv('my_csv.csv');

SELECT * FROM 'my_csv.csv';

For Excel files, only this will work

SELECT * FROM read_excel('my_excel.xlsx')

If you instead run

SELECT * FROM 'my_excel.xlsx'

you get

ExecutionException: Error during planning: unable to infer how to handle file extension: xlsx

[greyscaled]

Partially related: #2639 via #2602