Chapter on bug minimization

[langston-barrett]

This is covered in the new chapter on fuzzing, but bug minimization is a cross-cutting concern that deserves its own page. Should describe both manual techniques and automated tools.

Related content:

• rustc-dev-guide/src/backend/debugging.md

  Line 14 in 7cef03a

  ### Minimize the example

• rustc-dev-guide/src/fuzzing.md

  Line 87 in 7cef03a

  - Minimize the test case (see below)

I'm happy to work on this, though it might take me a few days to get started.