Control the file system used by the signature element

I will try to find time to review the patch.

Ideally, we should backport this patch to 8.x-5.x.

The failing test is very easy to fix.

Thanks Jrockowitz
I have updated the patch to fix the failing test.

We are testing it in GovCMS distribution

First off, the solution and approach are very good.

The attached patch has few tweaks

Created WebformElementFileDownloadAccessInterface
Improve readabilty of WebformSignature::accessFileDownload
Adds very basic test coverage

A few remaining questions/issues.

PDF generation with private signatures is not working. I think we can fix this.
@see \webform_entity_print_webform_submission_access

This patch add PDF support to the private signature element.

I think the last step is to add test coverage for including a "private" signature in PDFs via WebformEntityPrintFunctionalTest.php and webform.webform.test_entity_print.yml

If someone has time to manually review the patch, it would be greatly appreciated.

Added test coverage for including a "private" signature in PDFs via WebformEntityPrintFunctionalTest.php and webform.webform.test_entity_print.yml

Added test coverage for including a "private" signature in PDFs via WebformEntityPrintFunctionalTest.php and webform.webform.test_entity_print.yml

Change patch name to match with comment number.

Update the patch

This patch works with version 6.0.5.

This patch works with version 6.x-dev.

Default uri schema is private.

Another patch for 6.0.5 webform version.

This patch is for 6.0.5 version

I am hoping to do a manual review this week.

I am moving the patch to branch and PR (i.e. GitLab).

We must continue to support the public file system for signature elements to support backward compatibility.

Steps to manually review

• Apply patch or checkout branch
• Create new form with public and private signature elements
• Test new form
• Confirm public (/sites/default/files/webform/signature/s) and private (/system/files/webform/signature/) signature are using the expected base path.
• Confirm public file is accessible to anonymous users (http://localhost/wf/sites/default/files/webform/signature/signature_publ...)
• Confirm private file is not access to anonymous user and requires log-in (http://localhost/wf/system/files/webform/signature/signature_private/3/s...)
• Confirm PDF generation works as expected.
• Delete the submission and confirm both files are removed