feat: table widget uses "{f}" formatting of structs implementing a fo…

[tabre]

Allowing the Table widget to use the format() method of a struct when it is available might be a cleaner option, in some cases, than manually converting to a string before inclusion in the Table data.

The following struct would be rendered as a standard IP v4 address (x.x.x.x) in the Table widget:

const Server = struct {
    addr: Io.net.Ip4Address,

    pub fn format(self: Server, writer: anytype) !void {
        try writer.print("{d}.{d}.{d}.{d}", .{
            self.addr.bytes[0],
            self.addr.bytes[1],
            self.addr.bytes[2],
            self.addr.bytes[3]
        });
    }
};

[rockorager]

Thanks for the contribution! I added a small follow-up for optional values and merged it.