Demo of dynamic/configurable/optionally remote proj.db file

[carlopi]

Demo of projection database served over duckdbvfs barebone implementation.

To try this out:

1. Generate proj.db

#include <stdio.h>
#include "spatial/src/spatial/proj/proj_db.c"

int main(void)
{
    for (unsigned int i = 0; i < proj_db_len; i++)
        putchar(proj_db[i]);
    return 0;
}

g++ file.cpp -o generate_proj && ./generate_proj > proj.db
(should this part of the Makefile? Or it's already there?)

2. Launch http-server from the same folder where proj.db is

3. python3 duckdb/scripts/run_tests_one_by_one.py ./build/release/test/unittest '/Users/carlo/duckdblabs/duckdb_spatial/test/sql/*

TODO:

• Sort out context cleanup (see failure in unittester)
• Make location configurable via DuckDB option (should there be a MAP[extension_name] -> (MAP[option_name] -> option_value) to store extension options needed at load time ?
• Figure out whether proj.db should be fetched on load or anyhow proper strategy. Or maybe native have it backed in (who cares) but optionally configurable, and Wasm has it always remote

[carlopi]

This is still very immature, just a demo, I opened this by mistake, wanted to have it up on my fork. Moved over at carlopi#4 to discuss this.