feat: support specify the browser to use

Related: #405, #407, #397

crates/gpapi/src/process/auth_launcher.rs

@@ -19,6 +19,7 @@ pub struct SamlAuthLauncher<'a> {
   ignore_tls_errors: bool,
   clean: bool,
   default_browser: bool,
+  external_browser: Option<&'a str>,
 }
 
 impl<'a> SamlAuthLauncher<'a> {
@@ -35,6 +36,7 @@ impl<'a> SamlAuthLauncher<'a> {
       ignore_tls_errors: false,
       clean: false,
       default_browser: false,
+      external_browser: None,
     }
   }
 
@@ -88,6 +90,11 @@ impl<'a> SamlAuthLauncher<'a> {
     self
   }
 
+  pub fn external_browser(mut self, external_browser: Option<&'a str>) -> Self {
+    self.external_browser = external_browser;
+    self
+  }
+
   /// Launch the authenticator binary as the current user or SUDO_USER if available.
   pub async fn launch(self) -> anyhow::Result<Option<Credential>> {
     let mut auth_cmd = Command::new(GP_AUTH_BINARY);
@@ -133,6 +140,10 @@ impl<'a> SamlAuthLauncher<'a> {
       auth_cmd.arg("--default-browser");
     }
 
+    if let Some(external_browser) = self.external_browser {
+      auth_cmd.arg("--external-browser").arg(external_browser);
+    }
+
     let mut non_root_cmd = auth_cmd.into_non_root()?;
     let output = non_root_cmd
       .kill_on_drop(true)