Implemented mSlice on the VM allowing toOpenArray to work at compile time. (#20586)

* Implemented opcSlice to make 'toOpenArray' work on the VM

* Added nkOpenArray for VM to reduce bodgeness

* Fixed range issues and erraneous comments

* Range check correctly for openArrays in opcLdArr

* Inverted logic for ldArr checking

* vm now supports slicing strings

* Added string tests

* Removed usage of 'nkOpenArray' and redundant operations

* Refactored vmSlice implementation, removing redundant and incorrect code

* Made tuples go throw opcWrObj for field assignment

* All strkinds should be considered for openarrays

compiler/vmdef.nim

@@ -81,6 +81,7 @@ type
     opcWrStrIdx,
     opcLdStrIdx, # a = b[c]
     opcLdStrIdxAddr,  # a = addr(b[c])
+    opcSlice, # toOpenArray(collection, left, right)
 
     opcAddInt,
     opcAddImmInt,