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): veracrypt/VeraCrypt#1422

[zenmonkeykstop]

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

[cfm]

After brew upgrade --cask macfuse veracrypt on macOS 15.2, I can confirm veracrypt/VeraCrypt#1422's hdiutil: attach failed - no mountable file systems, resolved only by recreating the volume with the upgraded versions:

cfm@kintsugi ~ % sw_vers                                        
ProductName:		macOS
ProductVersion:		15.2
BuildVersion:		24C101
cfm@kintsugi ~ % /opt/homebrew/bin/brew info macfuse | head -n 1
==> macfuse: 4.8.3 (auto_updates)
cfm@kintsugi ~ % /opt/homebrew/bin/brew info veracrypt | head -n 1
==> veracrypt: 1.26.14

I'll file a pull request here with a warning that we can replicate to securedrop-workstation-docs once we're happy with it.

[cfm]

After #628 and freedomofpress/securedrop-workstation-docs#295, this is now blocked on veracrypt/VeraCrypt#1422.