Move UPLC dump into separate function + log event.

```
    Compiling aiken-lang/stdlib 43d8e740ffdf5febc59e51b7f0d5f8506115340c (examples/hello_world/build/packages/aiken-lang-stdlib)
    Compiling aiken-lang/hello_world 1.0.0 (examples/hello_world)
   Generating project's blueprint (examples/hello_world/plutus.json)
    Exporting UPLC (examples/hello_world/artifacts)
  ```

crates/aiken-project/src/lib.rs

@@ -184,6 +184,20 @@ where
         self.compile(options)
     }
 
+    pub fn dump_uplc(&self, blueprint: &Blueprint) -> Result<(), Error> {
+        let dir = self.root.join("artifacts");
+        self.event_listener
+            .handle_event(Event::DumpingUPLC { path: dir.clone() });
+        fs::create_dir_all(&dir)?;
+        for validator in &blueprint.validators {
+            // TODO: Also include validator name.
+            let path = dir.clone().join(format!("{}.uplc", validator.purpose));
+            fs::write(&path, validator.program.to_pretty())
+                .map_err(|error| Error::FileIo { error, path })?;
+        }
+        Ok(())
+    }
+
     pub fn compile(&mut self, options: Options) -> Result<(), Error> {
         self.compile_deps()?;
 
@@ -222,14 +236,7 @@ where
                 }
 
                 if uplc_dump {
-                    let dir = self.root.join("artifacts");
-                    fs::create_dir_all(&dir)?;
-                    for validator in &blueprint.validators {
-                        // TODO: Also include validator name.
-                        let path = dir.clone().join(format!("{}.uplc", validator.purpose));
-                        fs::write(&path, validator.program.to_pretty())
-                            .map_err(|error| Error::FileIo { error, path })?;
-                    }
+                    self.dump_uplc(&blueprint)?;
                 }
 
                 let json = serde_json::to_string_pretty(&blueprint).unwrap();

crates/aiken-project/src/telemetry.rs

@@ -22,6 +22,9 @@ pub enum Event {
     GeneratingBlueprint {
         path: PathBuf,
     },
+    DumpingUPLC {
+        path: PathBuf,
+    },
     GeneratingUPLCFor {
         name: String,
         path: PathBuf,