radicle: Return individual results for repo in `repositories_by_id` — heartwood

Change repositories_by_id to return Vec<Result<RepositoryInfo, RepositoryError>> instead of Result<Vec<RepositoryInfo>, RepositoryError>. This allows callers to handle failures on a per-repository basis rather than having the entire operation fail if a single repository lookup fails.

Previously, the method would stop processing and return an error as soon as any repository failed to load. Now it processes all repositories and returns individual results, making the API more resilient and giving callers more control over error handling.

 ### Changed
 - `radicle::storage::git::Storage::repositories_by_id` returns
   `impl Iterator<Item = Result<RepositoryInfo, RepositoryError>>` instead of
   `Result<Vec<RepositoryInfo>, RepositoryError>`. Allowing callers to handle
   failures on a per-repository basis rather than having the entire operation
   fail if a single repository lookup fails.
 - Re-exports from `git2` at `radicle::git::raw` were limited, using
   the heartwood workspace as a filter. Dependents that require members that
   are not exported anymore will have to depend on `git2` directly.

         self.path.as_path()
     }
     pub fn repositories_by_id<'a>(
     pub fn repositories_by_id<'a, I>(
         &self,
         mut rids: impl Iterator<Item = &'a RepoId>,
     ) -> Result<Vec<RepositoryInfo>, RepositoryError> {
         rids.try_fold(Vec::new(), |mut infos, rid| {
         rids: I,
     ) -> impl Iterator<Item = Result<RepositoryInfo, RepositoryError>> + use<'_, 'a, I>
     where
         I: Iterator<Item = &'a RepoId>,
     {
         rids.map(|rid| {
             let repo = self.repository(*rid)?;
             let (_, head) = repo.head()?;
             let refs = refs::SignedRefsAt::load(self.info.key, &repo)?;

                 .as_ref()
                 .map(|r| SyncedAt::new(r.at, &repo))
                 .transpose()?;
             let info = RepositoryInfo {
             Ok(RepositoryInfo {
                 rid: *rid,
                 head,
                 doc: repo.identity_doc()?.into(),
                 refs,
                 synced_at,
             };
             infos.push(info);
             Ok(infos)
             })
         })
     }