refactor: Fix typos in comments, configure cspell (#6164)

This change sets up a `cspell `configuration and fixes lots of typos in comments. There are no other code changes.

src/test/basics/IntrusiveShared_test.cpp

@@ -394,7 +394,7 @@ public:
             {
                 // strong goes out of scope while weak is still in scope
                 // This checks that partialDelete has run to completion
-                // before the desturctor is called. A sleep is inserted
+                // before the destructor is called. A sleep is inserted
                 // inside the partial delete to make sure the destructor is
                 // given an opportunity to run durring partial delete.
                 BEAST_EXPECT(cur == partiallyDeleted);