feat: add from_lines method

[Rjected]

This was motivated by an existing use case: parsing jemalloc memory profiles, for example like in rust-jemalloc-pprof. When parsing jemalloc memory profiles, the output of /proc/self/maps is included at the bottom of the file. Jemalloc profiles can be easily parsed using .lines(), so we already have a Lines data structure.

Providing a from_lines method, like the from_str method, would make parsing the proc maps from the profile extremely easy. Let me know what you think!

This would be consumed like this:

    // Parse the mappings from the file
    let maps = rsprocmaps::from_lines(lines);
    for map in maps {
        let map = map?;
        // ...
    }