Further parallelization of `VaultBuilder::build` 🚀🚀🚀

[Knut Magnus Aasrud]

Gotta go fast! Using something like Rayon, we should be able to parallelize the second notes pass:

mdzk/src/vault/builder.rs

Lines 168 to 191 in b056069

 notes.iter_mut().try_for_each(|(_, note)| { 
     note.adjacencies = adjacencies.clone(); 
     for_each_internal_link(&note.content.clone(), |link_string| { 
         match create_link(link_string, &path_lookup, &id_lookup) { 
             Ok(link) => { 
                 note.adjacencies 
                     .entry(link.dest_id) 
                     .and_modify(|adj| *adj = Edge::Connected); 
                 note.content = note.content.replacen( 
                     &format!("[[{}]]", link_string), 
                     &link.cmark(note.path.as_ref().unwrap().parent().unwrap()), 
                     1, 
                 ); 
             } 
             // NOTE: This error is currently ignored, but could be useful as a toggleable 
             // error, since that would allow users of mdzk to ensure all links have a valid 
             // destination on vault creation. 
             Err(Error::InvalidInternalLinkDestination(_)) => {} 
             Err(e) => return Err(e), 
         } 
  
         Ok(()) 
     }) 
 })?;