fix(js): Recognize more abs_paths as in-app (#1505)

The original logic for deciding whether a JS frame should be in-app
(seen at https://github.com/getsentry/sentry/blob/69ee8d0fcbff3494f2d2a6fb9fb59195fc49b575/src/sentry/lang/javascript/processor.py#L1573-L1603)
is quite convoluted and difficult to understand. The `is_in_app` function reproduces it faithfully,
but with some refactoring. In any case, for webpack, only file names beginning with `./` would be
considered as in-app, but judging from examples that's too strict. Therefore we change the logic for
webpack as follows: A file name is considered _not_ in-app if either of these is true:

* It starts with `~/` (according to the documentation in the original Python version, this means
  it's "coming from node_modules").
* It contains `/node_modules/` as a substring.

Otherwise it's considered in-app.

crates/symbolicator-js/src/utils.rs

@@ -111,9 +111,17 @@ pub fn fixup_webpack_filename(filename: &str) -> String {
     }
 }
 
+/// Returns whether the given abs_path and filename should be considered in-app.
+///
+/// This function was originally a simplified (but semantically faithful) version of
+/// <https://github.com/getsentry/sentry/blob/69ee8d0fcbff3494f2d2a6fb9fb59195fc49b575/src/sentry/lang/javascript/processor.py#L1573-L1603>.
+/// For a version that preserves the original exactly (modulo Python -> Rust translation), see
+/// `is_in_app_faithful`.
 pub fn is_in_app(abs_path: &str, filename: &str) -> Option<bool> {
     if abs_path.starts_with("webpack:") {
-        Some(filename.starts_with("./") && !filename.contains("/node_modules/"))
+        // This diverges from the original logic. Previously we would only consider
+        // a filename starting with `./` as in-app, but that seems to be overly strict.
+        Some(!filename.starts_with("~/") && !filename.contains("/node_modules/"))
     } else if abs_path.starts_with("app:") {
         Some(!NODE_MODULES_RE.is_match(filename))
     } else if abs_path.contains("/node_modules/") {
@@ -718,6 +726,20 @@ mod tests {
         assert_eq!(is_in_app(abs_path, filename), Some(true));
         assert_eq!(is_in_app_faithful(abs_path, filename), Some(true));
 
+        let abs_path = "webpack:///foo/bar/src/App.jsx";
+        let filename = "foo/bar/src/App.jsx";
+
+        // Here we have a discrepancy because the behavior of `is_in_app`
+        // longer aligns with that of the original Python version.
+        assert_eq!(is_in_app(abs_path, filename), Some(true));
+        assert_eq!(is_in_app_faithful(abs_path, filename), Some(false));
+
+        let abs_path = "webpack:///./foo/bar/App.tsx";
+        let filename = "./foo/bar/src/App.jsx";
+
+        assert_eq!(is_in_app(abs_path, filename), Some(true));
+        assert_eq!(is_in_app_faithful(abs_path, filename), Some(true));
+
         let abs_path = "webpack:///./node_modules/@sentry/browser/esm/helpers.js";
         let filename = "./node_modules/@sentry/browser/esm/helpers.js";