defaults to ORC (#19972)

* defaults to Orc

* bootstrap using refc

* use gc

* init orc defines

* unregister orc

* fix gc

* fix commands

* add prepareMutation for orc

* enable deepcopy for orc

* prepareMutation

* more fixes

* some cases

* bug #20081

* partial fixes

* partial fixes

* fixes command line

* more fixes

* build Nim with refc

* use gc

* more fixes

* rstore

* orc doesn't support threadpool

* more shallowCopy

* more fixes

* fixes unsafeNew

* workarounds

* small

* more fixes

* fixes some megatest

* tcodegenbugs1 refc

* fxies megatest

* build nimble with refc

* workaround tensordsl tests

* replace shallowCopy with move

* fixes action

* workaround

* add todo

* fixes important packages

* unpublic unregisterArcOrc

* fixes cpp

* enable windows

Co-authored-by: xflywind <43030857+xflywind@users.noreply.github.com>

tests/stdlib/tstring.nim

@@ -1,4 +1,5 @@
 discard """
+  matrix: "--mm:refc"
   targets: "c cpp js"
 """