`get_chars` method fails to decode UTF-8 bytes packed into integer

[stancld]

PDFium's FPDFText_GetUnicode returns unsigned 32-bit integer. Integers ≤ 1114111 are valid Unicode codepoint and can be converted with python in-built chr function. Larger integers are UTF-8 bytes packed into integers and must be handled separately.

Example

日 parsed pypdfium in UTF-8 int as: 15112101.

Current behavior

>>> chr(15112101)
ValueError: chr() arg not in range(0x110000)

Expected behavior

>>> utf8_int_to_string(15112101)
'日'

Suggestion

I will send a fix shortly.