message: Convert RegionValidationError from snafu to thiserror
diff: -use snafu::Snafu;
  use std::fmt::Debug;
  +use thiserror::Error;
  /// An error validating a Region
  -#[derive(Debug, Snafu)]
  +#[derive(Error, Debug)]
  #[non_exhaustive]
  pub enum RegionValidationError {
  - #[snafu(display(
  + #[error(
  "Region length exceeds capacity. Length {}, capacity {}",
  length,
  capacity
  - ))]
  - LengthExceedsCapacity {
  - length: u32,
  - capacity: u32,
  - backtrace: snafu::Backtrace,
  - },
  - #[snafu(display(
  + )]
  + LengthExceedsCapacity { length: u32, capacity: u32 },
  + #[error(
  "Region exceeds address space. Offset {}, capacity {}",
  offset,
  capacity
  - ))]
  - OutOfRange {
  - offset: u32,
  - capacity: u32,
  - backtrace: snafu::Backtrace,
  - },
  - #[snafu(display("Got a zero Wasm address in the offset"))]
  - ZeroOffset { backtrace: snafu::Backtrace },
  + )]
  + OutOfRange { offset: u32, capacity: u32 },
  + #[error("Got a zero Wasm address in the offset")]
  + ZeroOffset {},
  }
  impl RegionValidationError {
  pub(crate) fn length_exceeds_capacity(length: u32, capacity: u32) -> Self {
  - LengthExceedsCapacity { length, capacity }.build()
  + RegionValidationError::LengthExceedsCapacity { length, capacity }
  }
  pub(crate) fn out_of_range(offset: u32, capacity: u32) -> Self {
  - OutOfRange { offset, capacity }.build()
  + RegionValidationError::OutOfRange { offset, capacity }
  }
  pub(crate) fn zero_offset() -> Self {
  - ZeroOffset {}.build()
  + RegionValidationError::ZeroOffset {}
  }
  }
  