[OPENAPI to CADL] Parse x-ms-parameterized-host and security defintions

`x-ms-parameterized-host` maps to the `@server` decorator
https://microsoft.github.io/typespec/standard-library/rest/overview#server

security definitions can be mapped to elements for the authentication library
https://microsoft.github.io/typespec/standard-library/rest/authentication

Start by tracing the OPENAPI-to-CADL conversion entry point for x-ms-parameterized-host and security definitions, then read the linked TypeSpec REST documentation for @server and authentication. Done means both constructs map to the corresponding CADL elements; verify the converter's existing checks or tests once located.

Written by the indexing model from the issue text.