FindUnixCommands: Deprecate in favor of cmake -E

`${CMAKE_COMMAND} -E` subcommands are cross-platform replacements.

Fixes: #24263

Help/manual/cmake-modules.7.rst

@@ -251,7 +251,6 @@ They are normally called through the :command:`find_package` command.
    /module/FindTclStub
    /module/FindThreads
    /module/FindTIFF
-   /module/FindUnixCommands
    /module/FindVulkan
    /module/FindWget
    /module/FindWish
@@ -298,6 +297,7 @@ Deprecated Find Modules
    /module/FindPythonInterp
    /module/FindPythonLibs
    /module/FindQt
+   /module/FindUnixCommands
    /module/FindVTK
    /module/FindwxWindows
 

Modules/FindUnixCommands.cmake

@@ -5,6 +5,10 @@
 FindUnixCommands
 ----------------
 
+.. deprecated:: 3.26
+
+  Use :option:`${CMAKE_COMMAND} -E <cmake -E>` subcommands instead.
+
 Find Unix commands, including the ones from Cygwin
 
 This module looks for the Unix commands ``bash``, ``cp``, ``gzip``,