add test_divergent_cppstd_build_host test

[jcar87]

Changelog: Omit
Docs: Omit

[memsharded]

The possible fixes to change this behavior breaks #17643 added a couple of months ago for test_build_order_build_context_compatible() test.

If we change the behavior (it is easy), it might have implications for ConanCenter having missing binaries in the build context?

[memsharded]

To keep it for future reference.
If we ever want to change the behavior to require different build in "build" and "host", the change is:

diff --git a/conans/client/graph/graph_binaries.py b/conans/client/graph/graph_binaries.py 
index cc4334bda..43eaf4164 100644                                                          
--- a/conans/client/graph/graph_binaries.py                                                
+++ b/conans/client/graph/graph_binaries.py                                                
@@ -106,7 +106,7 @@ class GraphBinariesAnalyzer:                                           
         exactly the same                                                                  
         """                                                                               
         pref = node.pref                                                                  
-        previous_nodes = self._evaluated.get(pref)                                        
+        previous_nodes = self._evaluated.get((pref, node.context))                        
         if previous_nodes:                                                                
             previous_nodes.append(node)                                                   
             previous_node = previous_nodes[0]                                             
@@ -121,7 +121,7 @@ class GraphBinariesAnalyzer:                                           
             # https://github.com/conan-io/conan/issues/9880                               
             node._package_id = previous_node.package_id                                   
             return True                                                                   
-        self._evaluated[pref] = [node]                                                    
+        self._evaluated[(pref, node.context)] = [node]