[coro_file][improve]improve performance

[qicosmos]

Why

improve coro_file performance: make sure fopen, fread, fwrite, fclose in the same thread, otherwise will cause poor performance.

support pread and pwrite.

What is changing

Example

  coro_io::coro_file file{};
  co_await file.async_open(filename.data(), coro_io::flags::read_write);
  std::string str = "hello";

  {
    auto ec = co_await file.async_write(str.data(), str.size());
    std::string result;
    result.resize(10);
    file.seek(0, SEEK_SET);
    auto [rd_ec, size] = co_await file.async_read(result.data(), 5);
    std::string_view s(result.data(), size);
    CHECK(s == "hello");
  }

pread pwrite example: linux and enable USE_PREAD_WRITE

#if defined(__GNUC__) and defined(USE_PREAD_WRITE)
    coro_io::coro_file file{};
    async_simple::coro::syncAwait(
        file.async_open(filename.data(), coro_io::flags::read_write));
    CHECK(file.is_open());

    std::string buf = "cccccccccc";
    auto ec = async_simple::coro::syncAwait(
        file.async_write(0, buf.data(), buf.size()));
    CHECK(!ec);

    std::string buf1 = "dddddddddd";
    ec = async_simple::coro::syncAwait(
        file.async_write(10, buf1.data(), buf1.size()));
    CHECK(!ec);

    char buf2[100];
    auto pair = async_simple::coro::syncAwait(file.async_read(0, buf2, 10));
    CHECK(!file.eof());
    CHECK(std::string_view(buf2, pair.second) == "cccccccccc");

    pair = async_simple::coro::syncAwait(file.async_read(10, buf2, 10));
    CHECK(!file.eof());
    CHECK(std::string_view(buf2, pair.second) == "dddddddddd");
#endif