cast(json_extract(...) as <int-type>) does not convert quoted numbers

Noticed this while developing in the main branch, so putting down 13.1 as affected version, but likely affecting more GA versions.

For example, below the first statement fails to convert "3" to an unsigned integer, the second statement is able to do that, and the third statement is able to do the reverse:

select cast('[1, 42, "3"]'->'$[2]' as unsigned);

cast('[1, 42, "3"]'->'$[2]' as unsigned)

0

Warnings:

Warning	1292	Truncated incorrect INTEGER value: '"3"'

select substring('abcde', '[1, 42, "3"]'->'$[2]');

substring('abcde', '[1, 42, "3"]'->'$[2]')

cde

select cast('[1, 42, "3"]'->'$[0]' as char(1));

cast('[1, 42, "3"]'->'$[0]' as char(1))

1

select cast('[1, "42.567", "3"]'->'$[1]' as decimal(9,4));

cast('[1, "42.567", "3"]'->'$[1]' as decimal(9,4))

42.5670

Initial observation suggests the cause is that the first statement calls Item_func_json_extract::val_int_from_str, whereas the second calls Item_func_json_extract::val_int.

TODO: check what MDEV-38740 does, e.g. what happens if we do select cast(json('"3"') as unsigned)?