Reorganise the Access & Security tabs

Summary
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Break out the tabs from the Access & Security panel, currently under the Compute panel group, as the location confuses people.

Motivation
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This has been mentioned repeatedly, that users often find it confusing to locate items like Floating IPs.

Description
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Security Groups, Key Pairs, Floating IPs, and API Access are tabs under the Access & Security panel in the Compute panel group. We should split these tabs out into their own panels.

- Key Pairs will be moved to Project -> Compute -> Key Pairs
- Security Groups will be moved to Project -> Network -> Security Groups
- Floating IPs will be moved to Project -> Network -> Floating IPs
- API Access will be moved to Project -> API Access
- OpenStackRC v2/v3 download buttons will be added to the User dropdown in the top right of Horizon

UX
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The tabs mentioned above should ideally be easier for new users to discover.

Wireframes, Mocks, Videos and UI Markup
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N/A

Testing
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N/A

Outside Dependencies
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N/A

Requirements Update Required
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N/A

Doc Impact
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- Release note detailing the moves