[keyvault] Add warnings for usage of RSA-OAEP and RSA1_5

[maorleger]

Packages impacted by this PR

@azure/keyvault-keys

Issues associated with this PR

Resolves #32636
Resolves #32751

Describe the problem that is addressed by this PR

This PR accomplishes two goals:

1. Use generated enum names instead of overwriting them with our hand-authored
   ones in keyvault-keys
2. Adds a warning about using RSA1_5 and RSA-OAEP by proxy of (1) - exposing the
   generated enum names directly

What are the possible designs available to address the problem? If there are more than one possible design, why was the one in this PR chosen?

Are there test cases added in this PR? (If not, why?)

Provide a list of related PRs (if any)

https://github.com/Azure/azure-rest-api-specs/pull/32422/files should be
//approved and merged before this can be merged.

Command used to generate this PR: (Applicable only to SDK release request PRs)

Checklists

• Added impacted package name to the issue description.
• Does this PR need any fixes in the SDK Generator?** (If so, create an Issue in the Autorest/typescript repository and link it here.)
• Added a changelog (if necessary).

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

@azure/keyvault-keys