Add azuredeploy.json for key-vault-key-create

[msmbaldwin]

Adds azuredeploy.json for the key-vault-key-create sample.

Why?

azuredeploy.json was missing from #14706 under the (incorrect) assumption that CI would regenerate the compiled JSON from main.bicep automatically. AQT doesn't do that — both files are expected to be committed by the contributor, and the "Deploy to Azure" / "Visualize" buttons in README.md link directly to azuredeploy.json.

How was it generated?

az bicep build against the main.bicep already on master.

[azure-quickstarts]

@msmbaldwin - check this PR for updates that may be needed to documentation that references this sample. [This is an automated message. You are receiving it because you are listed as the docOwner in metadata.json.]

[msmbaldwin]

@alex-frankel — quick explanation and ask:

When the four KV RBAC PRs (#14704, #14705, #14706, #14707) were prepared, azuredeploy.json was deleted under the (wrong) assumption that CI would regenerate it from main.bicep. It doesn't, and the "Deploy to Azure" buttons in each README.md link directly to azuredeploy.json — so the merged samples are currently broken.

This PR (and its three siblings #14740, #14741, #14742) just adds the missing azuredeploy.json, generated via az bicep build from the main.bicep already on master. No template logic changes.

MAC is green on all four. The red "Validate" check is the same testResult-required-vs-MAC-schema-rejects-it conflict you merged through on the original PRs. Could you take a look when you have a minute? Thanks!