Add modal confirm deletion

[Saga6569]

Description

Please describe here what changes are made and why.
Added the ability to hide the cross in the base of the modal component
Added a modal window to confirm the deletion of Flow
Changed text color from #000000 to #000000E5
Removed Slots node in Nodes list
In slots node -> edit group -> the new slot button should have white text and the save button should have white background

Checklist

• I have performed a self-review of the changes

List here tasks to complete in order to mark this PR as ready for review.

To Consider

• Add tests (if functionality is changed)
• Update API reference / tutorials / guides
• Update CONTRIBUTING.md (if devel workflow is changed)
• Update .ignore files, scripts (such as lint), distribution manifest (if files are added/deleted)
• Search for references to changed entities in the codebase