Code review feedback changes.

* Add `anyhow` dependency to `wasmtime-runtime`.
* Revert `get_data` back to `fn`.
* Remove `DataInitializer` and box the data in `Module` translation instead.
* Improve comments on `MemoryInitialization`.
* Remove `MemoryInitialization::OutOfBounds` in favor of proper bulk memory
  semantics.
* Use segmented memory initialization except for when the uffd feature is
  enabled on Linux.
* Validate modules with the allocator after translation.
* Updated various functions in the runtime to return `anyhow::Result`.
* Use a slice when copying pages instead of `ptr::copy_nonoverlapping`.
* Remove unnecessary casts in `OnDemandAllocator::deallocate`.
* Better document the `uffd` feature.
* Use WebAssembly page-sized pages in the paged initialization.
* Remove the stack pool from the uffd handler and simply protect just the guard
  pages.

crates/runtime/src/instance/allocator/pooling/unix.rs

@@ -1,4 +1,5 @@
 use crate::Mmap;
+use anyhow::{anyhow, Result};
 
 pub unsafe fn make_accessible(addr: *mut u8, len: usize) -> bool {
     region::protect(addr, len, region::Protection::READ_WRITE).is_ok()
@@ -20,7 +21,7 @@ pub unsafe fn decommit(addr: *mut u8, len: usize) {
     );
 }
 
-pub fn create_memory_map(accessible_size: usize, mapping_size: usize) -> Result<Mmap, String> {
+pub fn create_memory_map(accessible_size: usize, mapping_size: usize) -> Result<Mmap> {
     Mmap::accessible_reserved(accessible_size, mapping_size)
-        .map_err(|e| format!("failed to allocate pool memory: {}", e))
+        .map_err(|e| anyhow!("failed to allocate pool memory: {}", e))
 }