`lldb-server platform --server` works on Windows now w/o multithreading. The rest functionality remains unchanged. Fixes #90923, fixes #56346. This is the part 1 of the replacement of #100670. In the part 2 I plan to switch `lldb-server gdbserver` to use `--fd` and listen a common gdb port for all gdbserver connections. Then we can remove gdb port mapping to fiх #97537.