Chore: Delta table writes should be able to use relative paths for COPY TO

[talagluck]

Description

Currently, COPY TO for all data types except for Delta tables allows for relative paths, e.g.

COPY (SELECT 1) TO './my_file.csv';

However, when copying to a Delta table, it requires the path to be specified in the following way:

COPY (SELECT 1) TO 'file:///Users/path/to/your_new_delta_table';

In addition to being inconsistent with the other file types, it is also less convenient, particularly for an embedded use-case. Ideally, Delta tables could be copied to in the same way as other file types, e.g.:

COPY (SELECT 1) TO './my_delta_table';