Update layout for the "New DAST scan" page

What does this MR do and why?

This MR resolves #354879 (closed)

1. It changes layout to two column layout according to new design
2. Page header is updated to 'New on-demand scan'
3. Manage scans action is removed from header sections after this discussion
4. Scanner profile and Site profile are unchanged as it is a part of #355640 (closed)
5. Scan schedule is using toggle now and updated according to new design
6. Scan type is readonly.
7. The idea of refactoring is to create a layout similar to this page. section-layout component is a simple wrapper around previously existed code, that creates a two column layout, which is responsive for different viewports.

Describe in detail what your merge request does and why.

Screenshots or screen recordings

before

after
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on-demand-scan-layout

These are strongly recommended to assist reviewers and reduce the time to merge your change.

How to set up and validate locally

1. Go to any project /root/$PROJECT/
2. Go to /root/$PROJECT/-/on_demand_scans#/all
3. Create new scan or edit existing one.

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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