cli: show revision on rad patch checkout — heartwood

Help the user know which revision they currently have checked out when running rad patch checkout.

 ✓ Fetching rad:z42hL2jL4XNk6K8oHQaSWfMgCL7ji from z6MknSL…StBU8Vi..
 ✓ Fetched repository from 1 seed(s)
 $ rad patch checkout aa45913 --name alice-init
 ✓ Switched to branch alice-init
 ✓ Switched to branch alice-init at revision aa45913
 ✓ Branch alice-init setup to track rad/patches/aa45913e757cacd46972733bddee5472c78fa32a
 ```

 ``` ~bob
 $ rad patch checkout aa45913 -f --name alice-init
 ✓ Switched to branch alice-init
 ✓ Switched to branch alice-init at revision 3156bed
 $ git status
 On branch alice-init
 Your branch is up to date with 'rad/patches/aa45913e757cacd46972733bddee5472c78fa32a'.

 ```
 $ rad patch checkout aa45913 --revision 3156bed9d64d4675d6cf56612d217fc5f4e8a53a -f
 ✓ Switched to branch patch/aa45913
 ✓ Switched to branch patch/aa45913 at revision 3156bed
 ```
 And we can confirm that the current commit corresponds to `27857ec`:

 ```
 $ rad patch checkout aa45913e757cacd46972733bddee5472c78fa32a
 ✓ Switched to branch patch/aa45913
 ✓ Switched to branch patch/aa45913 at revision aa45913
 ✓ Branch patch/aa45913 setup to track rad/patches/aa45913e757cacd46972733bddee5472c78fa32a
 ```

 ```
 $ git checkout master -q
 $ rad patch checkout aa45913
 ✓ Switched to branch patch/aa45913
 ✓ Switched to branch patch/aa45913 at revision aa45913
 ```
 Now, let's add a README too!

 ``` ~alice
 $ rad patch checkout 55b9721ed7f6bfec38f43729e9b6631c5dc812fb
 ✓ Switched to branch patch/55b9721
 ✓ Switched to branch patch/55b9721 at revision 55b9721
 ✓ Branch patch/55b9721 setup to track rad/patches/55b9721ed7f6bfec38f43729e9b6631c5dc812fb
 $ git show
 commit bdcdb30b3c0f513620dd0f1c24ff8f4f71de956b

 f2de534b5e81d7c6e2dcaf58c3dd91573c0a0354
 $ git checkout master -q
 $ rad patch checkout d004b67
 ✓ Switched to branch patch/d004b67
 ✓ Switched to branch patch/d004b67 at revision d004b67
 ✓ Branch patch/d004b67 setup to track rad/patches/d004b67355456c46de10c0d287e4a791ad1a6945
 $ rad remote add z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk
 ✓ Follow policy updated for z6Mkt67GdsW7715MEfRuP4pSZxJRJh6kj6Y48WRqVv4N1tRk

 ```
 $ rad patch checkout e4934b6d9dbe01ce3c7fbb5b77a80d5f1dacdc46
 ✓ Switched to branch patch/e4934b6
 ✓ Switched to branch patch/e4934b6 at revision 773b9aa
 ✓ Branch patch/e4934b6 setup to track rad/patches/e4934b6d9dbe01ce3c7fbb5b77a80d5f1dacdc46
 $ git mv REQUIREMENTS REQUIREMENTS.md
 $ git commit -m "Use markdown for requirements"

         .get(patch_id)?
         .ok_or_else(|| anyhow!("Patch `{patch_id}` not found"))?;
     let revision = match revision_id {
         Some(id) => patch
             .revision(&id)
             .ok_or_else(|| anyhow!("Patch revision `{id}` not found"))?,
         None => patch.latest().1,
     let (revision_id, revision) = match revision_id {
         Some(id) => (
             id,
             patch
                 .revision(&id)
                 .ok_or_else(|| anyhow!("Patch revision `{id}` not found"))?,
         ),
         None => patch.latest(),
     };
     let mut spinner = term::spinner("Performing checkout...");

     working.set_head(&git::refs::workdir::branch(&patch_branch))?;
     spinner.message(format!(
         "Switched to branch {}",
         term::format::highlight(&patch_branch)
         "Switched to branch {} at revision {}",
         term::format::highlight(&patch_branch),
         term::format::secondary(term::format::oid(revision_id)),
     ));
     spinner.finish();