strict effects (#18777)

* fixes #17369
* megatest is green for --cpu:arm64
* docgen output includes more tags/raises
* implemented 'effectsOf' 
* algorithm.nim: uses new effectsOf annotation
* closes #18376
* closes #17475
* closes #13905
* allow effectsOf: [a, b]
* added a test case
* parameters that are not ours cannot be declared as .effectsOf
* documentation
* manual: added the 'sort' example
* bootstrap with the new better options

lib/std/private/globs.nim

@@ -8,13 +8,18 @@ import os
 when defined(windows):
   from strutils import replace
 
+when defined(nimHasEffectsOf):
+  {.experimental: "strictEffects".}
+else:
+  {.pragma: effectsOf.}
+
 type
   PathEntry* = object
     kind*: PathComponent
     path*: string
 
 iterator walkDirRecFilter*(dir: string, follow: proc(entry: PathEntry): bool = nil,
-    relative = false, checkDir = true): PathEntry {.tags: [ReadDirEffect].} =
+    relative = false, checkDir = true): PathEntry {.tags: [ReadDirEffect], effectsOf: follow.} =
   ## Improved `os.walkDirRec`.
   #[
   note: a yieldFilter isn't needed because caller can filter at call site, without