Instantiates generics in the module that uses it (#22513)

Attempts to move the generic instantiation to the module that uses it.
This should decrease re-compilation times as the source module where the
generic lives doesnt need to be recompiled

---------

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

tests/ic/tgenericinst.nim

@@ -0,0 +1,11 @@
+discard """
+  cmd: "nim cpp --incremental:on $file"
+"""
+
+{.emit:"""/*TYPESECTION*/
+#include <iostream>
+  struct Foo { };
+""".}
+
+type Foo {.importcpp.} = object
+echo $Foo() #Notice the generic is instantiate in the this module if not, it wouldnt find Foo