Fix_deprecation_utf8_decode

[LuisParada7]

Updated the strlen1 function in the Iconv class to use mb_strlen for character counting. This change addresses the deprecation of utf8_decode in PHP 8.2 and ensures accurate character counting for UTF-8 strings, including those with multi-byte characters. The pollyfill-iconv component has not yet been updated to reflect this deprecation, making this change necessary for compatibility with newer PHP versions.

[Julian-Tovar]

Hi @LuisParada7 thank you for your contribution. At this point in time we are opting to use the Core library to solve this issue. In particular we are going to use \core_text::convert which does the same as the utf8 encode and decode functions. The advantage of using the Core library is that we leave the implementation details to Core, so that if in the future, the mb_strlen function or any other is deprecated, we don't have to change anything, because Core will change the implementation details inside of \core_text::convert. Thanks again.