fix: respect useAuthWithCustomEndpoint flag for resumable uploads

[pm990320]

Description

Fixes resumable uploads to respect the useAuthWithCustomEndpoint configuration flag when using custom API endpoints.

Problem

Currently, resumable uploads automatically bypass authentication for any non-googleapis.com domain, even when useAuthWithCustomEndpoint: true is explicitly set. This prevents using authenticated proxies or custom storage endpoints with resumable uploads.

Solution

• Pass useAuthWithCustomEndpoint flag through to resumable upload configuration
• Only bypass authentication if the flag is not explicitly set to true
• Add useAuthWithCustomEndpoint property to Service class for proper type-safe access
• Maintains backward compatibility with existing behavior

Changes Made

1. src/nodejs-common/service.ts

• Added useAuthWithCustomEndpoint?: boolean to ServiceConfig interface
• Added useAuthWithCustomEndpoint?: boolean property to Service class
• Store the value in the Service constructor

2. src/file.ts

• Pass useAuthWithCustomEndpoint from Storage to resumable upload config

3. src/resumable-upload.ts

• Added useAuthWithCustomEndpoint?: boolean to UploadConfig interface
• Modified authentication bypass logic to check the flag before bypassing auth

4. test/resumable-upload.ts

• Added test: "should use authentication with custom endpoint when useAuthWithCustomEndpoint is true"
• Added test: "should bypass authentication with custom endpoint when useAuthWithCustomEndpoint is false"
• Added test: "should bypass authentication with custom endpoint when useAuthWithCustomEndpoint is undefined (backward compatibility)"

Testing

• ✅ All new tests passing
• ✅ Existing tests still pass
• ✅ TypeScript compilation successful
• ✅ Linting passed

Use Case

This fix is needed for:

• Using authenticated proxies for GCS (e.g., nginx caching proxy with auth forwarding)
• Corporate environments with custom storage gateways
• Development environments with authenticated mock servers
• Any scenario requiring resumable uploads through an authenticated intermediary

Backward Compatibility

✅ Fully maintained - when useAuthWithCustomEndpoint is undefined, the behavior remains unchanged (bypasses auth for custom endpoints)

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[ddelgrosso1]

Thank you for the PR @pm990320. Before we review, do you mind signing the CLA?

[pm990320]

Thank you for the PR @pm990320. Before we review, do you mind signing the CLA?

Hey @ddelgrosso1 - I have now signed the CLA.