cli: branch: inline view.remove_branch() in cmd_branch_forget()

This API no longer makes sense, and we'll probably add some flags to forget
only tracked remotes for example.

cli/src/commands/branch/forget.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use itertools::Itertools as _;
-use jj_lib::op_store::BranchTarget;
+use jj_lib::op_store::{BranchTarget, RefTarget, RemoteRef};
 use jj_lib::str_util::StringPattern;
 use jj_lib::view::View;
 
@@ -47,8 +47,13 @@ pub fn cmd_branch_forget(
     let repo = workspace_command.repo().clone();
     let matched_branches = find_forgettable_branches(repo.view(), &args.names)?;
     let mut tx = workspace_command.start_transaction();
-    for (name, _) in &matched_branches {
-        tx.mut_repo().remove_branch(name);
+    for (name, branch_target) in &matched_branches {
+        tx.mut_repo()
+            .set_local_branch_target(name, RefTarget::absent());
+        for (remote_name, _) in &branch_target.remote_refs {
+            tx.mut_repo()
+                .set_remote_branch(name, remote_name, RemoteRef::absent());
+        }
     }
     tx.finish(
         ui,

lib/src/repo.rs

@@ -1428,10 +1428,6 @@ impl MutableRepo {
         self.view.mark_dirty();
     }
 
-    pub fn remove_branch(&mut self, name: &str) {
-        self.view_mut().remove_branch(name);
-    }
-
     pub fn get_local_branch(&self, name: &str) -> RefTarget {
         self.view.with_ref(|v| v.get_local_branch(name).clone())
     }

lib/src/view.rs

@@ -96,14 +96,6 @@ impl View {
         self.data.head_ids.remove(head_id);
     }
 
-    // TODO: maybe rename to forget_branch() because this seems unusual operation?
-    pub fn remove_branch(&mut self, name: &str) {
-        self.data.local_branches.remove(name);
-        for remote_view in self.data.remote_views.values_mut() {
-            remote_view.branches.remove(name);
-        }
-    }
-
     /// Iterates local branch `(name, target)`s in lexicographical order.
     pub fn local_branches(&self) -> impl Iterator<Item = (&str, &RefTarget)> {
         self.data