fix(r/adbcdrivermanager): Use std::vector<uint8_t> instead of std::basic_string<uint8_t>

[paleolimbot]

Because it makes more sense, but also with clang18, CRAN reports a warning:

In file included from driver_test.cc:24:
In file included from ./driver_base.h:19:
In file included from /usr/local/clang-trunk/bin/../include/c++/v1/memory:939:
In file included from /usr/local/clang-trunk/bin/../include/c++/v1/__memory/shared_ptr.h:21:
In file included from /usr/local/clang-trunk/bin/../include/c++/v1/__fwd/ostream.h:13:
/usr/local/clang-trunk/bin/../include/c++/v1/__fwd/string.h:45:41: warning: 'char_traits<unsigned char>' is deprecated: char_traits<T> for T not equal to char, wchar_t, char8_t, char16_t or char32_t is non-standard and is provided for a temporary period. It will be removed in LLVM 19, so please migrate off of it. [-Wdeprecated-declarations]
   45 | template <class _CharT, class _Traits = char_traits<_CharT>, class _Allocator = allocator<_CharT> >
      |                                         ^
./driver_base.h:168:20: note: in instantiation of default argument for 'basic_string<uint8_t>' required here
  168 |         const std::basic_string<uint8_t>& value = GetBytesUnsafe();
      |                    ^~~~~~~~~~~~~~~~~~~~~
/usr/local/clang-trunk/bin/../include/c++/v1/__string/char_traits.h:81:8: note: 'char_traits<unsigned char>' has been explicitly marked deprecated here
   81 | struct _LIBCPP_DEPRECATED_(
      |        ^
/usr/local/clang-trunk/bin/../include/c++/v1/__config:933:53: note: expanded from macro '_LIBCPP_DEPRECATED_'
  933 | #      define _LIBCPP_DEPRECATED_(m) __attribute__((__deprecated__(m)))
      |                                                     ^

[lidavidm]

FWIW, I think it should work to write

std::vector<uint8_t> cppvalue(value, value + length);

(constructor (5) here https://en.cppreference.com/w/cpp/container/vector/vector)

[paleolimbot]

That is way better (thank you!)