Print and show error end locations

[ilevkivskyi]

Using the flag --show-error-end the errors will be output like file:line:column:end_line:end_column, for example:

x: int = "no way"
main:1:10:1:17: error: Incompatible types in assignment (expression has type "str", variable has type "int")

This will be helpful for various tools to highlight error location. Also when run with --pretty mypy itself will highlight the full span of error context (except if it spans multiple lines, like Python 3.11 itself does). Examples:

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[ilevkivskyi]

@JukkaL All tests pass finally, you can review this now.

[JukkaL]

Looks good! This makes error reporting more user friendly, and tracking the end line/column could be useful for other things as well in the future.