It's time to add common functions to the internal 'common' package.
- Add the function that read the contents from a file to a list.
- Add the function that parses a list of integers from a string.
...and more to come later...
- added a custom function to check if a rune is a symbol.
- changed name of type 'answer' to 'solution'.
- ci(forgejo actions): updated setup-go from v3 to v4.
