[KeyVault] Add samples for new certificate SANs (IP/URI) and secret secret_encoding/previous_version features

[rohitsinghal4u]

Description

This PR adds sample code demonstrating new KeyVault features:

Certificates

• IP addresses in Subject Alternative Names (SANs) via san_ip_addresses
• URIs in Subject Alternative Names (SANs) via san_uris

Secrets

• secret_encoding parameter for format conversion (PFX/PEM)
• previous_version property on SecretProperties

Files Changed

• sdk/keyvault/azure-keyvault-certificates/samples/hello_world.py
• sdk/keyvault/azure-keyvault-secrets/samples/hello_world.py

[Copilot]

Pull request overview

This PR updates Key Vault hello_world samples to demonstrate recently added features in the azure-keyvault-certificates and azure-keyvault-secrets SDKs.

Changes:

• Certificates sample: adds san_ip_addresses and san_uris to CertificatePolicy usage.
• Secrets sample: adds commentary/examples around retrieving certificate-backed secrets in alternate encodings and printing SecretProperties.previous_version.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
sdk/keyvault/azure-keyvault-certificates/samples/hello_world.py	Extends certificate policy sample to include IP and URI SAN fields.
sdk/keyvault/azure-keyvault-secrets/samples/hello_world.py	Adds sample guidance for certificate-backed secret output encoding and previous_version.

[Copilot]

The sample refers to a secret_encoding keyword argument, but SecretClient.get_secret uses out_content_type (see azure.keyvault.secrets._client.SecretClient.get_secret). As written, uncommenting this line would raise TypeError: get_secret() got an unexpected keyword argument 'secret_encoding'. Update the sample text and example call to use out_content_type=ContentType.PEM (or the equivalent MIME type string).

Suggested change

	# For certificate-backed secrets, we can retrieve the secret in a different encoding format using secret_encoding.
	# For example, to get a PFX-backed certificate secret in PEM format:
	# pem_secret = client.get_secret(secret.name, secret_encoding=ContentType.PEM)
	# For certificate-backed secrets, we can retrieve the secret in a different encoding format using out_content_type.
	# For example, to get a PFX-backed certificate secret in PEM format:
	# pem_secret = client.get_secret(secret.name, out_content_type=ContentType.PEM)

[Copilot]

The comment says previous_version applies to “secrets created after June 1, 2025”, but the generated model docs state it applies only to certificates created after that date and only for certificate-backed secrets. Please reword this comment to avoid implying all secrets will have version history via previous_version.

Suggested change

	# For secrets created after June 1, 2025, previous_version tracks version history.
	# This is useful for certificate-backed secrets.
	# For certificate-backed secrets, previous_version may be populated to indicate the prior version.
	# This applies to certificates created after June 1, 2025, and should not be assumed for all secrets.