refactor: Rename ripple namespace to xrpl (#5982)

This change renames all occurrences of `namespace ripple` and `ripple::` to `namespace xrpl` and `xrpl::`, respectively, as well as the names of test suites. It also provides a script to allow developers to replicate the changes in their local branch or fork to avoid conflicts.

src/test/unit_test/multi_runner.cpp

@@ -10,7 +10,7 @@
 #include <sstream>
 #include <vector>
 
-namespace ripple {
+namespace xrpl {
 
 namespace detail {
 
@@ -636,4 +636,4 @@ template class multi_runner_base<true>;
 template class multi_runner_base<false>;
 }  // namespace detail
 
-}  // namespace ripple
+}  // namespace xrpl