feat: Add toggle button to view secrets as YAML

[kiran-4444]

Description

What does this PR do?

This PR adds the ability to view secrets as YAML. The design is minimal and was implemented to see the expected behaviour. I need help in polishing this further.

Fixes #29481

TODO only if you're a HashiCorp employee

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  of a public function, even if that change is in a CE file, double check that
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  break any tests. Sometimes ENT only tests rely on public functions in CE
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[hashicorp-cla-app]

All committers have signed the CLA.

[kiran-4444]

@heatherezell Can you take a look at this? Thanks!

[Monkeychip]

@kiran-4444 thank you so much for the PR. The KV secrets engine is widely used, and any feature we add has to go through a longer design process. I have surfaced this PR to design, but there is no larger need for this feature at the moment.