Do not parse --max-fps float in the client

Many parsing and formatting C functions like strtof() and asprintf() are
locale-dependent. Forcing a C locale just for the conversions in a way
that works on all platforms is a mess.

In practice, this is not a problem, scrcpy always uses the C locale,
because it never calls:

    setlocale(LC_ALL, "");

But the max-fps option should not depend on the locale configuration
anyway.

Since the value is parsed by the client in Java anyway, just forward the
string value as is.

app/src/options.h

@@ -240,7 +240,7 @@ struct scrcpy_options {
     uint16_t max_size;
     uint32_t video_bit_rate;
     uint32_t audio_bit_rate;
-    float max_fps;
+    const char *max_fps; // float to be parsed by the server
     enum sc_lock_video_orientation lock_video_orientation;
     enum sc_orientation display_orientation;
     enum sc_orientation record_orientation;