Closes https://github.com/zed-industries/zed/issues/31870 Release Notes: - Allowed opening 1 more item if `n` tabs are pinned, where `n` equals `max_tabs` count. - Fixed a bug where pinned tabs would eventually be closed out when exceeding the `max_tabs` count. - Fixed a bug where a tab could be lost when pinning a tab while at the `max_tabs` count. - Fixed a bug where pinning a tab when already at the `max_tabs` limit could cause other tabs to be incorrectly closed.