The text input control_event was initially designed for mapping
SDL_TextInputEvent, limited to 32 characters.
For simplicity, the copy/paste feature was implemented using the same
control_event: it just sends the text to paste.
However, the pasted text might have a length breaking some assumptions:
- on the client, the event max-size was smaller than the text
max-length,
- on the server, the raw buffer storing the events was smaller than the
max event size.
Fix these inconsistencies, and encode the length on 2 bytes, to accept
more than 256 characters.
Fixes <https://github.com/Genymobile/scrcpy/issues/10>.