[C#] Add support for the ping pong test, bring support for futures that return strings, i.e. types returned via pointers. (#1606)

* add support for the ping-pong test.

Requires supporting futures that return strings.

* address feedback, remove redundant parameters and duplicate Callback function

* add example for regex

Author: yowl

.gitignore

@@ -9,3 +9,5 @@ ace
 __pycache__
 crates/guest-rust/src/cabi_realloc.o
 wit_component
+
+/wit-bindgen.sln

Cargo.lock

@@ -1256,7 +1256,7 @@ impl<'a, B: Bindgen> Generator<'a, B> {
                 // based on slightly different logic for the `task.return`
                 // intrinsic.
                 //
-                // Note that in the async import case teh code below deals with the CM function being lowered,
+                // Note that in the async import case the code below deals with the CM function being lowered,
                 // not the core function that is underneath that (i.e. func.result may be empty,
                 // where the associated core function underneath must have a i32 status code result)
                 let (lower_to_memory, async_flat_results) = match (async_, &func.result) {

crates/core/src/abi.rs

@@ -28,6 +28,7 @@ heck = { workspace = true }
 clap = { workspace = true, optional = true }
 anyhow = { workspace = true }
 indexmap = { workspace = true }
+regex = "1.12.3"
 
 [features]
 default = ["aot"]