fix(folder): pass rootFolderId when folderId params is null

[bivanalhar]

Problem Statement

Folder could not be created when we just entered the Materials page through clicking in Sidebar

Root Cause

Before PR #7626, we don't have any notions of undefined folderId, which means when we navigate to any folders inside any course, we always pass on the valid folderId as URL parameter. However, the mentioned PR introduced the notion of undefined folderId in which it's actually referring to root folder.

Even though we handled the case of when folderId is undefined by redirecting to root Folder page, the value folderId itself remains undefined and hence it's rendered as NaN when being passed on to backend for root parent Id

Resolving the Issue

When creating the New Folder, instead of merely relying on folderId, we modified that line to be using folderId if it's defined, otherwise we use currFolderInfo.id which is what's supposed to be the folderId in the first place (in case of folderId is undefined, currFolderInfo refers to root folder)

[cysjonathan]

• add test to check able to create new folder from root folder (to prevent regression)
• fixed incorrect redirection to parent folder when editing current folder
• add autofocus on folder title when dialog opens