rename std/threads to std/typedthreads (#20850)

* rename `std/threads` to `std/oldthreads`

* fixes tests

* rename to `typedthreads`

* changelog

lib/pure/concurrency/threadpool.nim

@@ -23,7 +23,7 @@ when not compileOption("threads"):
 import cpuinfo, cpuload, locks, os
 
 when defined(nimPreviewSlimSystem):
-  import std/[assertions, threads]
+  import std/[assertions, typedthreads]
 
 {.push stackTrace:off.}
 

lib/system.nim

@@ -2071,9 +2071,9 @@ when not defined(js):
     when hostOS != "standalone":
       include system/threadimpl
       when not defined(nimPreviewSlimSystem):
-        {.deprecated: "threads is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/threads`".}
-        import std/threads
-        export threads
+        {.deprecated: "threads is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/typedthreads`".}
+        import std/typedthreads
+        export typedthreads
 
   elif not defined(nogc) and not defined(nimscript):
     when not defined(useNimRtl) and not defined(createNimRtl): initStackBottom()