CIs: attempt to use csources_v1 (#16282)

* CIs: attempt to use csources_v1
* also updated the BSDs
* also updated azure pipelines
* std modules should not itself use the 'std/' import dir...
* compiler has to be careful with std/ for v1 booting

(cherry picked from commit a9b62de895)

lib/pure/os.nim

@@ -943,6 +943,8 @@ proc expandTilde*(path: string): string {.
   ## Windows: this is still supported despite Windows platform not having this
   ## convention; also, both ``~/`` and ``~\`` are handled.
   ##
+  ## **Warning**: `~bob` and `~bob/` are not yet handled correctly.
+  ##
   ## See also:
   ## * `getHomeDir proc <#getHomeDir>`_
   ## * `getConfigDir proc <#getConfigDir>`_

lib/std/monotimes.nim

@@ -74,7 +74,7 @@ when defined(js):
     system.`+`(a, b)
   {.pop.}
 
-elif defined(posix):
+elif defined(posix) and not defined(osx):
   import posix
 
 elif defined(windows):

lib/std/wrapnils.nim

@@ -1,6 +1,6 @@
 ## This module allows chains of field-access and indexing where the LHS can be nil.
 ## This simplifies code by reducing need for if-else branches around intermediate values
-## that maybe be nil.
+## that may be nil.
 ##
 ## Note: experimental module and relies on {.experimental: "dotOperators".}
 ## Unstable API.
@@ -82,7 +82,7 @@ template `[]`*(a: Wrapnil): untyped =
   else:
     default(T)
 
-import std/macros
+import macros
 
 proc replace(n: NimNode): NimNode =
   if n.kind == nnkPar: