Add GOV Notify integration for notifications

[CodeSureUK]

Introduced GOV Notify as a new notification provider, enabling support for email and SMS notifications via the GOV.UK Notify API. Updated relevant components, configuration, and dependencies to support this integration. This includes a dedicated form for GOV Notify in the notification dialog and backend logic for message handling.

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Description

Fixes #(issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• User interface (UI)
• New feature (non-breaking change which adds functionality)
• Breaking change (a fix or feature that would cause existing functionality to not work as expected)
• Other
• This change requires a documentation update

Checklist

• My code follows the style guidelines of this project
• I ran ESLint and other linters for modified files
• I have performed a self-review of my own code and tested it
• I have commented my code, particularly in hard-to-understand areas (including JSDoc for methods)
• My changes generates no new warnings
• My code needed automated testing. I have added them (this is optional task)

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