LimitInvalidError on big Filedata

[NotStatilko]

The Telethon library throws LimitInvalidError when we try to download a RemoteBoxFile with big filedata (e.g where folder len equals to FOLDERNAME_MAX)

tgbox/api.py

Lines 929 to 931 in 17025f3

	filedata_len = bytes_to_int(dec_navbytes[:3],signed=False)
	preview_len = bytes_to_int(dec_navbytes[3:],signed=False)
	#TODO: BIG FILEDATA LEN IS BROKEN

This error already was reported to Telethon devs.
LonamiWebs/Telethon#3199 (comment)

Anyway, we should investigate this.