update minidump crate prereqs

Fix memreader ub

Fix Yama blocking child-to-parent ptrace

feat: Update `minidump` crates

Reorganizes a bunch of code and also updates some things to use emerging Rust
best-practices.

- Change use statements to use blocks
- Prefer to use `super::` rather than `crate::` where applicable
- Use mod.rs in a directory instead of <modname>.rs when a module has
  submodules
- Move error type definitions closer to where they are used
  - Most error types are pretty specific to a tight scope, so put them there
  - Exception is the MinidumpWriter's error type - There's so much code that
    it's better to put it in its own module
- Merge PtraceDumper and MinidumpWriter
  - The split between them has been blurry for a while
  - Merge them and their error types together
  - A nice thing about the split was that `MinidumpWriter` had a bit of a
    "builder config" behavior for `PtraceDumper`. Let's keep that!
  - There is now a `MinidumpWriterConfig` that is explicitly a fluent API used
    to configure `MinidumperWriter`
- Change functions that were tightly coupled to `MinidumpWriter` to just be
  impls on it
- Update tests to accept new structure

Fixes #154

Merge PtraceDumper and MinidumpWriter

Updated all dependencies removing a large number of duplications