fix(bindings): handle accessMode in runtime bindings with OPFS

[sumimakito]

This is an amazing project with many great works. Thank you

Context

During my recent usage with duckdb-wasm with the recent OPFS support done by @e1arikawa (Thank you for the cool work!), I encountered an issue where the file/directory handles were always created even when I opened the database with read-only options like:

db.open({
    path: 'opfs://not_yet_existing.db',
    accessMode: DuckDBAccessMode.READ_ONLY, // We should NOT create any files/directories
})

Summary

Going deeper, it seems we didn't handle the accessMode in helper functions like prepareFileHandles. Therefore, in this pull request, I tried to add the missing parameters to these functions as optional ones and added several test cases for open operations as such with different accessMode in OPFS.