Display environment loading failures in the activity indicator (#18567)

As @maan2003 noted in #18473, we should warn the user if direnv call
fails

Release Notes:

- Show a notice in the activity indicator if an error occurs while
loading the shell environment

crates/project/src/direnv.rs

@@ -0,0 +1,72 @@
+use crate::environment::EnvironmentErrorMessage;
+use std::process::ExitStatus;
+
+#[cfg(not(any(test, feature = "test-support")))]
+use {collections::HashMap, std::path::Path, util::ResultExt};
+
+#[derive(Clone)]
+pub enum DirenvError {
+    NotFound,
+    FailedRun,
+    NonZeroExit(ExitStatus, Vec<u8>),
+    EmptyOutput,
+    InvalidJson,
+}
+
+impl From<DirenvError> for Option<EnvironmentErrorMessage> {
+    fn from(value: DirenvError) -> Self {
+        match value {
+            DirenvError::NotFound => None,
+            DirenvError::FailedRun | DirenvError::NonZeroExit(_, _) => {
+                Some(EnvironmentErrorMessage(String::from(
+                    "Failed to run direnv. See logs for more info",
+                )))
+            }
+            DirenvError::EmptyOutput => None,
+            DirenvError::InvalidJson => Some(EnvironmentErrorMessage(String::from(
+                "Direnv returned invalid json. See logs for more info",
+            ))),
+        }
+    }
+}
+
+#[cfg(not(any(test, feature = "test-support")))]
+pub async fn load_direnv_environment(dir: &Path) -> Result<HashMap<String, String>, DirenvError> {
+    let Ok(direnv_path) = which::which("direnv") else {
+        return Err(DirenvError::NotFound);
+    };
+
+    let Some(direnv_output) = smol::process::Command::new(direnv_path)
+        .args(["export", "json"])
+        .env("TERM", "dumb")
+        .current_dir(dir)
+        .output()
+        .await
+        .log_err()
+    else {
+        return Err(DirenvError::FailedRun);
+    };
+
+    if !direnv_output.status.success() {
+        log::error!(
+            "Loading direnv environment failed ({}), stderr: {}",
+            direnv_output.status,
+            String::from_utf8_lossy(&direnv_output.stderr)
+        );
+        return Err(DirenvError::NonZeroExit(
+            direnv_output.status,
+            direnv_output.stderr,
+        ));
+    }
+
+    let output = String::from_utf8_lossy(&direnv_output.stdout);
+    if output.is_empty() {
+        return Err(DirenvError::EmptyOutput);
+    }
+
+    let Some(env) = serde_json::from_str(&output).log_err() else {
+        return Err(DirenvError::InvalidJson);
+    };
+
+    Ok(env)
+}