cli: Add `--seeds` option to `ls`

Small addition that is useful.

radicle-cli/examples/rad-clone.md

@@ -65,7 +65,7 @@ Date:   Mon Jan 1 14:39:16 2018 +0000
 
 Cloned repositories show up in `rad ls`:
 ```
-$ rad ls --all
+$ rad ls --seeds
 ╭───────────────────────────────────────────────────────────────────────────────────────────────────────────╮
 │ Name        RID                                 Visibility   Head      Description                        │
 ├───────────────────────────────────────────────────────────────────────────────────────────────────────────┤

radicle-cli/examples/rad-unseed.md

@@ -21,6 +21,8 @@ Now, if we run `rad ls`, we see it's gone:
 ```
 $ rad ls
 Nothing to show.
+$ rad ls --seeds
+Nothing to show.
 ```
 
 However, with the `--all` flag, we can see it still, but as local-only:

radicle-cli/src/commands/ls.rs

@@ -23,7 +23,8 @@ Options
 
     --private       Show only private repositories
     --public        Show only public repositories
-    --all           Show all repositories in storage
+    --seeds, -s     Show all seeded repositories
+    --all, -a       Show all repositories in storage
     --verbose, -v   Verbose output
     --help          Print help
 "#,
@@ -35,6 +36,7 @@ pub struct Options {
     public: bool,
     private: bool,
     all: bool,
+    seeds: bool,
 }
 
 impl Args for Options {
@@ -46,15 +48,19 @@ impl Args for Options {
         let mut private = false;
         let mut public = false;
         let mut all = false;
+        let mut seeds = false;
 
         while let Some(arg) = parser.next()? {
             match arg {
                 Long("help") | Short('h') => {
                     return Err(Error::Help.into());
                 }
-                Long("all") => {
+                Long("all") | Short('a') => {
                     all = true;
                 }
+                Long("seeds") | Short('s') => {
+                    seeds = true;
+                }
                 Long("private") => {
                     private = true;
                 }
@@ -72,6 +78,7 @@ impl Args for Options {
                 private,
                 public,
                 all,
+                seeds,
             },
             vec![],
         ))
@@ -103,7 +110,7 @@ pub fn run(options: Options, ctx: impl term::Context) -> anyhow::Result<()> {
         if !doc.visibility.is_public() && !options.private && options.public {
             continue;
         }
-        if refs.is_none() && !options.all {
+        if refs.is_none() && !options.all && !options.seeds {
             continue;
         }
         let seeded = policy.is_seeding(&rid)?;
@@ -111,6 +118,9 @@ pub fn run(options: Options, ctx: impl term::Context) -> anyhow::Result<()> {
         if !seeded && !options.all {
             continue;
         }
+        if !seeded && options.seeds {
+            continue;
+        }
         let proj = doc.project()?;
         let head = term::format::oid(head).into();