fs: avoid unhandled rejection in filehandle readableWebStream close

[jorgitin02]

Fixes: #56116

When FileHandle emits 'close', readableWebStream currently calls readableStreamCancel(readable) without handling rejection. If the stream has already errored (for example after EBADF), this can surface as an unhandled rejection.

This change consumes that cancel rejection on the close-notify path.

Tests:

• add regression for errored readableWebStream + explicit file.close() (no unhandled rejection)
• add BYOB variant for the same edge path
• keep a success-path safety check

[jorgitin02]

CC @nodejs/fs @nodejs/streams

This PR targets #56116.

What it changes:

• Handles the readableStreamCancel(readable) rejection on FileHandle 'close' notification path.
• Prevents unhandled rejection when the stream is already errored (e.g. EBADF) and close-notify triggers cancel.

Why:

• readableWebStream() could surface an unhandled rejection in this edge sequence:

1. stream read errors
2. FileHandle emits 'close'
3. close handler calls readableStreamCancel(readable) without consuming rejection

Tests added:

• Regression: errored readableWebStream() + explicit file.close() does not crash due to unhandled rejection.
• Edge: same path with BYOB reader.
• Safety: successful read/close path remains unaffected.

Validation run:

• ./node test/parallel/test-filehandle-readablestream-error-close.js
• ./node test/parallel/test-filehandle-readablestream.js