Merge branch '406724-ce-paste-loading' into 'master'

Show a loading indicator on pasting markdown in rich text editor

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/123202



Merged-by: Kushal Pandya <kushal@gitlab.com>
Approved-by: Ankit Panchal <apanchal@gitlab.com>
Approved-by: Kushal Pandya <kushal@gitlab.com>
Reviewed-by: Lukas 'Eipi' Eipert <leipert@gitlab.com>
Reviewed-by: Kushal Pandya <kushal@gitlab.com>
Reviewed-by: Himanshu Kapoor <info@fleon.org>
Reviewed-by: Ankit Panchal <apanchal@gitlab.com>
Co-authored-by: Himanshu Kapoor <hkapoor@gitlab.com>