Remove hard breaks in plain-text emails

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

latest

Problem you are trying to solve

For reasons I do not understand, breaking lines at 72 characters in plain text emails is a historical standard, instead of delegating such line wrapping to email clients. As K-9 is a mobile client the screen is of course smaller - and so this line wrapping acts contrary to its intended purpose, making emails much harder to read. I frequently receive emails that look like the following:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed
 do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut enim
 ad minim
veniam, quis nostrud exercitation ullamco laboris nisi ut
 aliquip ex ea
commodo consequat. Duis aute irure dolor in reprehenderit in
 voluptate
velit esse cillum dolore eu fugiat nulla pariatur. Excepteur
 sint
occaecat cupidatat non proident, sunt in culpa qui officia
 deserunt
mollit anim id est laborum.

Suggested solution

It would be nice if K-9 would take a "Markdown approach" to line breaks in plain-text emails and wrap them nicely.

Screenshots / Drawings / Technical details

No response

The issue names no files, tests, or entry points. Start by locating the plain-text email rendering and current 72-character wrapping behavior, then identify how the requested wrapping should interact with existing message formatting; done means plain-text messages are readable without forced hard breaks and the behavior is covered by tests.