Add "Go to file", "Delete Directory" to repo file list page (#35911)

/claim #35898
Resolves #35898 

### Summary of key changes:

1. Add file name search/Go to file functionality to repo button row.
2. Add backend functionality to delete directory
3. Add context menu for directories with functionality to copy path & delete a directory
4. Move Add/Upload file dropdown to right for parity with Github UI
5. Add tree view to the edit/upload UI

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/v1/repo/file.go

@@ -610,10 +610,6 @@ func handleChangeRepoFilesError(ctx *context.APIContext, err error) {
 		ctx.APIError(http.StatusUnprocessableEntity, err)
 		return
 	}
-	if git.IsErrBranchNotExist(err) || files_service.IsErrRepoFileDoesNotExist(err) || git.IsErrNotExist(err) {
-		ctx.APIError(http.StatusNotFound, err)
-		return
-	}
 	if errors.Is(err, util.ErrNotExist) {
 		ctx.APIError(http.StatusNotFound, err)
 		return