Bug 1831434 - Make `EditorBase::InsertNodeWithTransaction` return error if...

Bug 1831434 - Make `EditorBase::InsertNodeWithTransaction` return error if inserted node is moved by JS r=m_kato

Some handlers, e.g., `HTMLWithContextInserter` may want to skip post processing
after inserting new node instead of immediately stop handling the action.
Currently, `HTMLWithContextInserter` correctly ignores the cases only when
`NS_ERROR_EDITOR_UNEXPECTED_DOM_TREE` is required.  Therefore, making
`InsertNodeWithTransaction` return the error makes `HTMLWithContextInserter`
work correctly in tricky cases.

Differential Revision: https://phabricator.services.mozilla.com/D177446