[TS] Fix relative paths for exports (#8517)

Fixes an issue where exports were using incorrect relative paths for
>=3 namespace levels. This is fixed by making the starting range of the
namespace components relative to the amount of components.

Co-authored-by: Björn Harrtell <bjornharrtell@users.noreply.github.com>

tests/ts/tsconfig.json

@@ -15,6 +15,8 @@
     "namespace_test/**/*.ts",
     "union_vector/**/*.ts",
     "arrays_test_complex/**/*.ts",
-    "union_underlying_type_test.ts"
+    "union_underlying_type_test.ts",
+    "long-namespace/**/*.ts",
+    "longer-namespace/**/*.ts"
   ]
 }