Document/assess VeraCrypt macOS compatibility issues

[eloquence]

We've heard user reports of macOS compatibility issues (at least on M1 Macs) with recent versions of Veracrypt / macOS. Let's assess current compatibility and workarounds, and amend our docs accordingly, as we recommend Veracrypt specifically for cross-platform compatibility both for classic SD and SDW.

• https://docs.securedrop.org/en/stable/admin/installation/set_up_transfer_and_export_device.html
• https://workstation.securedrop.org/en/stable/admin/reference/provisioning_usb.html

[eloquence]

Possibly related upstream ticket (thanks Ro): https://github.com/veracrypt/VeraCrypt/issues/1422

[zenmonkeykstop]

Sounds like it will still work with volumes created under Sequoia - that might be worth verifying if we have anyone running that.