treewide: migrate from boost::adaptors::transformed to std::views::transform

now that we are allowed to use C++23. we now have the luxury of using
`std::views::transform`.

in this change, we:

- replace `boost::adaptors::transformed` with `std::views::transform`
- use `fmt::join()` when appropriate where `boost::algorithm::join()`
  is not applicable to a range view returned by `std::view::transform`.
- use `std::ranges::fold_left()` to accumulate the range returned by
  `std::view::transform`
- use `std::ranges::fold_left()` to get the maximum element in the
  range returned by `std::view::transform`
- use `std::ranges::min()` to get the minimal element in the range
  returned by `std::view::transform`
- use `std::ranges::equal()` to compare the range views returned
  by `std::view::transform`
- remove unused `#include <boost/range/adaptor/transformed.hpp>`

to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.

this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.

limitations:

there are still a couple places where we are still using
`boost::adaptors::transformed` due to the lack of a C++23 alternative
for `boost::join()` and `boost::adaptors::uniqued`.

Signed-off-by: Kefu Chai <[email protected]>

Author: tchaikov

sstables_loader.cc

@@ -279,7 +279,7 @@ future<> sstable_streamer::stream_sstables(const dht::partition_range& pr, std::
         auto ops_uuid = streaming::plan_id{utils::make_random_uuid()};
         llog.info("load_and_stream: started ops_uuid={}, process [{}-{}] out of {} sstables=[{}]",
             ops_uuid, nr_sst_current, nr_sst_current + sst_processed.size(), nr_sst_total,
-            fmt::join(sst_processed | boost::adaptors::transformed([] (auto sst) { return sst->get_filename(); }), ", "));
+            fmt::join(sst_processed | std::views::transform([] (auto sst) { return sst->get_filename(); }), ", "));
         nr_sst_current += sst_processed.size();
         co_await stream_sstable_mutations(ops_uuid, pr, std::move(sst_processed));
         if (on_streamed) {