Add OPFS (Origin Private File System) Support

[e1arikawa]

Description:

This PR implements OPFS (Origin Private File System) support in the latest version of duckdb-wasm based on PR #1490.
This allows database files to be read and written to the OPFS.

API:
When opening a database file, you can now use the following API:

await db.open({
    path: 'opfs://test.db',
    accessMode: duckdb.DuckDBAccessMode.READ_WRITE,
});
const conn = await db.connect();

Changes:

• Added support for OPFS.
  • Bug Fixes:
    • Resolved issues related to COPY TO functionality.
    • Fixed support for signed S3 URLs.

[carlopi]

This is very very welcome, thanks.

I am in the process of releasing a new version of duckdb-wasm, connected to duckdb 1.1.0.
Once that is out, I will properly review this PR.

[e1arikawa]

@carlopi
Thank you very much for your update and for taking the time to review this PR.
I look forward to your feedback once the release is out.
Please let me know if there's anything I can assist with in the meantime.

[carlopi]

One comment would be if you could have a look at the failing test

[e1arikawa]

@carlopi
I have merged the latest main branch and confirmed that the tests using DuckDB 1.1.1 pass successfully.

https://github.com/AKABANAKK/duckdb-wasm/actions/runs/11016245572

[carlopi]

Thanks, I gave a proper look, this looks solid, thanks a lot for the contribution.

This PR does introduces some API changes that might be somewhat unexpected, so I think the proper way forward would be:

• tag v1.29.0 (later today)
• merge this PR / iterate
• tag v1.30.0 in the next weeks

[e1arikawa]

@carlopi
Thank you for reviewing my contribution. Regarding the API changes, I will carefully test them after tagging v1.29.0.
Please proceed with the work as per your proposed plan. I appreciate your continued support.

[e1arikawa]

@carlopi
I will be using the release version that includes this PR for my work. Therefore, I would like to ask when the PR will be merged. If there is anything I can do to assist with the merge process, please let me know. Thank you for your time and support.