Support for passing no_read/write_workqueue to cryptsetup

[refi64]

A while back, Cloudflare did a blog post where they detailed some changes they made to improve their performance under LUKS, involving two new cryptsetup flags, no_read_workqueue and no_write_workqueue. I figured I'm give them a try...but, as it turns out, Stratis doesn't have any way of passing custom values to cryptsetup. For testing purposes, I added the new flags to libcryptsetup-rs (I'm aware this probably won't build on older libcryptsetup-rs versions, but for testing, this was fine) and then unconditionally activated cryptsetup with the relevant flags. After some pain in getting it installed (tried to build the RPM but didn't feel like figuring out how to get the cryptsetup-rs changes into mockbuild), I can confirm it any optionsdoes work, though I have no idea if it's faster or not yet.

Regardless, it would be nice to have this as an option. This brings me to the problem I realized as I was adding this, which is that there is doesn't seem to be a generic way to pass options to pool activation 😅 so instead of trying to PR changes, I'm opening this to figure out what a plan to get this implemented would be!