Remove the old path.
Rename path2 to path.
Update all clients for the new path.
Also make some miscellaneous changes to the Path APIs to help the
adoption process.
These methods return an object that can be formatted using {} to print
display strings.
Path itself does not implement fmt::Default to avoid accidental usage of
display strings in incorrect places (e.g. process arguments).
These functions are for working with a string representation of the path
even if it's not UTF-8 encoded. They replace invalid UTF-8 sequences
with the replacement char.
