Add --prefer-text option

Expose an option to configure how key/text events are forwarded to the
Android device.

Enabling the option avoids issues when combining multiple keys to enter
special characters, but breaks the expected behavior of alpha keys in
games (typically WASD).

Fixes <https://github.com/Genymobile/scrcpy/issues/650>

app/src/scrcpy.h

@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 #include "config.h"
+#include "input_manager.h"
 #include "recorder.h"
 
 struct scrcpy_options {
@@ -24,6 +25,7 @@ struct scrcpy_options {
     bool display;
     bool turn_screen_off;
     bool render_expired_frames;
+    bool prefer_text;
 };
 
 #define SCRCPY_OPTIONS_DEFAULT { \
@@ -43,6 +45,7 @@ struct scrcpy_options {
     .display = true, \
     .turn_screen_off = false, \
     .render_expired_frames = false, \
+    .prefer_text = false, \
 }
 
 bool