Add ST_Read_Meta, don't throw in GDAL filesystem stat

[Maxxen]

This PR adds a new st_read_meta table function to read the metadata present in files readable by st_read.
The output is similar to what you would get with ogrinfo -json but some fields are still missing. (like e.g. metadata ironically). Still, this finally allows you to inspect the projection info of a GDAL dataset layer from within DuckDB.

Closes #156

Also implements a small fix in the gdal virtual filesystem layer so that a failed stat call doesn't throw but instead returns -1.

[cboettig]

@Maxxen is this available in the nightlies? I'm trying to test with:

FORCE INSTALL 'spatial' FROM 'http://nightly-extensions.duckdb.org';
LOAD 'spatial'

But I still get the error:

Error: Catalog Error: Table Function with name st_read_meta does not exist!
Did you mean "st_read"?

[Maxxen]

@cboettig What version are you on? Seems to work for me on v0.9.2

As well as on V0.10.0

[cboettig]

my apologies! just updated and it's working now, (v0.9.2) thanks.