Modernise design for admin notices.

[aaronfc]

Hello @aaronfc and friends 👋 I took a look at this and I was wondering if we could make them look similar to the Sensei ones, so we get some consistency going.

Here's what I have for you:

Not sure if I missed anything, so do let me know. Figma file is here.

@burtrw

Originally posted by @Luchadores in https://github.com/Automattic/WP-Job-Manager/issues/2379#issuecomment-1481336928

Success Criteria:

• [ ] All different styles are supported for the wpjm admin notices.
• [ ] All existing notices have been migrated to the new design.
• [ ] All existing notices are dismissible – including the one about addon updates.

[aaronfc]

Related PR: https://github.com/Automattic/WP-Job-Manager/pull/2383

[github-actions[bot]]

Closed by #2401.