Reading UTF-8 char by char in C

The provided code is designed to read a file and print its contents to the console, handling UTF-8 characters by determining the length of each character using the utf8_length function. This function checks the binary representation of each character to determine if it is a 1, 2, 3, or 4-byte UTF-8 character, and returns the corresponding length. The main function reads the file character by character, checks the length of each character using the utf8_length function, and prints the entire character to the console. The test file contains a variety of characters, including non-ASCII characters such as emojis, accented letters, and characters from different languages, to test the code's ability to handle UTF-8 encoding.