Fixed #36611, Refs #36580 -- Added system check for multicolumn ForeignObject in Meta.indexes/constraints/unique_together.

ForeignObjects with multiple `from_fields` are not supported in these
options.

Co-authored-by: Jacob Walls <jacobtylerwalls@gmail.com>
Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>

docs/ref/checks.txt

@@ -443,6 +443,9 @@ Models
 * **models.E048**: ``constraints/indexes/unique_together`` refers to a
   ``CompositePrimaryKey`` ``<field name>``, but ``CompositePrimaryKey``\s are
   not supported for that option.
+* **models.E049**: ``constraints/indexes/unique_together`` refers to a
+  ``ForeignObject`` ``<field name>`` with multiple ``from_fields``, which is
+  not supported for that option.
 
 Management Commands
 -------------------

docs/releases/6.0.txt

@@ -295,6 +295,10 @@ Models
   don't support it (MySQL and MariaDB), the fields are marked as deferred to
   trigger a refresh on subsequent accesses.
 
+* Using a :ref:`ForeignObject <cpk-and-relations>` with multiple
+  ``from_fields`` in Model indexes, constraints, or :attr:`unique_together
+  <django.db.models.Options.unique_together>` now emits a system check error.
+
 Pagination
 ~~~~~~~~~~