[lldb] update lldb-server platform help parsing (#162730)

The lldb-server platform help text is inconsistent with lldb-server
gdbserver help text. This PR modernizes the platform server to use
LLVM's [TableGen](https://llvm.org/docs/TableGen/)-based option parsing
(matching the existing gdbserver implementation), which auto-generates
option parsing code and help text.

The changes improve documentation quality by adding comprehensive option
descriptions,, adding support for `-h`/`--help` flags, and organizing
help output with DESCRIPTION and EXAMPLES sections. Internal-only
options (`--child-platform-fd`) and unused legacy options (`--debug`,
`--verbose`) are now hidden from help while maintaining backward
compatibility. All functional behavior remains unchanged—this is purely
a documentation and code modernization improvement.

## before
```
> /opt/llvm/bin/lldb-server p -h
p: unrecognized option '-h'
Usage:
  /opt/llvm/bin/lldb-server p [--log-file log-file-name] [--log-channels log-channel-list] [--port-file port-file-path] --server --listen port
```

## after
```
lldb-server p -h 
OVERVIEW: lldb-server platform

USAGE: lldb-server p [options] --listen <[host]:port> [[--] program args...]

CONNECTION OPTIONS:
  --gdbserver-port <port> Port to use for spawned gdbserver instances. If 0 or unspecified, a port will be chosen automatically. Short form: -P
  --listen <[host]:port>  Host and port to listen on. Format: [host]:port or protocol://[host]:port (e.g., tcp://localhost:1234, unix:///path/to/socket). Short form: -L
  --socket-file <path>    Write listening socket information (port number for TCP or path for Unix domain sockets) to the specified file. Short form: -f

GENERAL OPTIONS:
  --help            Display this help message and exit.
  --log-channels <channel1 categories...:channel2 categories...>
                    Channels to log. A colon-separated list of entries. Each entry starts with a channel followed by a space-separated list of categories. Common channels: lldb, gdb-remote, platform, process. Short form: -c
  --log-file <file> Destination file to log to. If empty, log to stderr. Short form: -l
  --server          Run in server mode, accepting multiple client connections sequentially. Without this flag, the server exits after handling the first connection.

OPTIONS:
  -- program args Arguments to pass to launched gdbserver instances.

DESCRIPTION
  Acts as a platform server for remote debugging. When LLDB clients connect,
  the platform server handles platform operations (file transfers, process
  launching) and spawns debug server instances (lldb-server gdbserver) to
  handle actual debugging sessions.

  By default, the server exits after handling one connection. Use --server
  to keep running and accept multiple connections sequentially.

EXAMPLES
  # Listen on port 1234, exit after first connection
  lldb-server platform --listen tcp://0.0.0.0:1234

  # Listen on port 5555, accept multiple connections
  lldb-server platform --server --listen tcp://localhost:5555

  # Listen on Unix domain socket
  lldb-server platform --listen unix:///tmp/lldb-server.sock

```

For comparison, here is the **gdbserver** help text:
```
lldb-server g -h
OVERVIEW: lldb-server

USAGE: lldb-server g[dbserver] [options] [[host]:port] [[--] program args...]

CONNECTION:
  --fd <fd>           Communicate over the given file descriptor.
  --named-pipe <name> Write port lldb-server will listen on to the given named pipe.
  --pipe <fd>         Write port lldb-server will listen on to the given file descriptor.
  --reverse-connect   Connect to the client instead of passively waiting for a connection. In this case [host]:port denotes the remote address to connect to.

GENERAL OPTIONS:
  --help            Prints out the usage information for lldb-server.
  --log-channels <channel1 categories...:channel2 categories...>
                    Channels to log. A colon-separated list of entries. Each entry starts with a channel followed by a space-separated list of categories.
  --log-file <file> Destination file to log to. If empty, log to stderr.
  --setsid          Run lldb-server in a new session.

TARGET SELECTION:
  --attach <pid-or-name> Attach to the process given by a (numeric) process id or a name.
  -- program args        Launch program for debugging.

DESCRIPTION
  lldb-server connects to the LLDB client, which drives the debugging session.
  If no connection options are given, the [host]:port argument must be present
  and will denote the address that lldb-server will listen on. [host] defaults
  to "localhost" if empty. Port can be zero, in which case the port number will
  be chosen dynamically and written to destinations given by --named-pipe and
  --pipe arguments.

  If no target is selected at startup, lldb-server can be directed by the LLDB
  client to launch or attach to a process.
```