colw/Reduce lag when switching staking tabs.

[colw]

Description:

Keep validator list in memory.

This wraps the router-view with the <keep-alive> component which keeps dynamic components in memory when switched out.

Thank you! 🚀

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For contributor:

• Added changes entries. Run yarn changelog for a guided process.
• Reviewed Files changed in the github PR explorer
• Attach screenshots of the UI components on the PR description (if applicable)
• Scope of work approved for big PRs

For reviewer:

• Manually tested the changes on the UI

[faboweb]

Neat!