fix(codecatalyst): "Open Dev Environment" fails on flatpak #3416

Problem:
"Open CodeCatalyst Dev Environment" fails on flatpak (steamdeck).

Solution:
Prefer the special flatpak path `/app/bin/code`, instead of the
$appRoot-relative path inferred from the current vscode process.

Author: justinmk3

.changes/next-release/Bug Fix-141dd557-3cb2-4651-a93e-afdaffca9637.json

@@ -0,0 +1,4 @@
+{
+	"type": "Bug Fix",
+	"description": "\"Open CodeCatalyst Dev Environment\" fails on flatpak (steamdeck)"
+}

src/shared/systemUtilities.ts

@@ -197,6 +197,9 @@ export class SystemUtilities {
         const vscExe = process.argv0
         // https://github.com/microsoft/vscode-test/blob/4bdccd4c386813a8158b0f9b96f31cbbecbb3374/lib/util.ts#L133
         const vscs = [
+            // Special case for flatpak (steamdeck). #V896741845
+            // https://github.com/flathub/com.visualstudio.code/blob/master/code.sh
+            '/app/bin/code',
             // Note: macOS does not have a separate "code-insiders" binary.
             path.resolve(`${vscode.env.appRoot}/bin/code`), // macOS
             path.resolve(`${vscode.env.appRoot}/../../bin/code`), // Windows