Include /proc/cmdline in WhisperBack bug reports

This will allow us to “compute stats about how much I2P is used in Tails” (#11672 (closed)), and apparently frontdesk would like to see this info as well for other reasons.

Feature Branch: doc/10543-dotfiles-for-apt

Related issues

Has duplicate #11666 (closed)
Blocks #11672 (closed)

Original created by @intrigeri on 11675 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information