dsh-better-sidebar-svn: Add SVN Panel to DSH Sidebar

`dsh-better-sidebar-svn` is an SVN management plugin for the DSH web sidebar, designed to address the lack of convenient access points for SVN operations within projects. The plugin relies on `dsh-better-sidebar >=0.12.0` and the system `svn` command-line tool (1.7+), implementing its functions by calling non-interactive SVN commands with XML output. Its core functions include distinguishing "staged/unstaged" in the status panel; file Diff viewing that supports keyword search and quick navigation; staged commit based on Changelist; as well as `svn update`, file restore, ignore rule maintenance, paginated history viewing, and quick conflict resolution. The plugin possesses a fault tolerance mechanism; when SVN is missing from the system or component rendering is abnormal...