fix #19149 Invalid codegen when returning var tuple from a template (#20762)

* fix #19149 Invalid codegen when returning var tuple from a template

* fix type

(cherry picked from commit bae0fb720a)

tests/template/t19149.nim

@@ -0,0 +1,19 @@
+type Foo = tuple[active: bool, index: int]
+
+
+var f: Foo
+
+# template result type during match stage
+# f:var Foo
+# a:Foo
+# tyVar
+# tyTuple
+# after change to proc
+# f:Foo
+# a:Foo
+# tyTuple
+# tyTuple
+
+template cursor(): var Foo = f
+discard cursor()
+