chore(IWYU): Remove some redundant includes

[KaganCanSit]

Checked header dependencies using IWYU and removed includes identified as redundant. I check potential false positives and some warnings were addressed here — not all.

fmt project has platform-specific guards and backward-compatibility build paths that's why I tried to approach it as minimally as possible.

I am marking this PR draft. I want analyze CI results and check again this changes.

[KaganCanSit]

#include "fmt/os.h"  // fmt::system_category
#include "fmt/ranges.h"
#include "gtest-extra.h"  // StartsWith

#ifdef __cpp_lib_filesystem
TEST(std_test, path) {
  using std::filesystem::path;
// ...
// ...
// ...
// ...
  EXPECT_EQ(fmt::format("{:?}", path(L"\xD800")), "\"\\ud800\"");
#  endif
}

// Intentionally delayed include to test #4303
#  include "fmt/ranges.h"

fmt/test/std-test.cc have two same include fmt/ranges.h. But If I change compile failed. I'll take a look at it when I have time. (I need to find the test purpose of the second include.)

[vitaut]

LGTM. Do you still plan to make changes to this PR or shall we merge?

[KaganCanSit]

LGTM. Do you still plan to make changes to this PR or shall we merge?

Thank you for your review. We can mergw. At the moment, I haven’t been able to find the time to look into the situation I mentioned in the comment above.

[vitaut]

Merged, thanks!