Property 'apiVersion' does not exist on type 'DataMapContext'

[v-jiaodi]

for @azure-rest/purview-datamap, set is-modular-library true, build error as follow:

for Azure.Analytics.Purview.DataMap case:
expected code export interface DataMapContext extends Client { /** The API version to use for this operation. */ apiVersion: string; } but generate code is export interface DataMapContext extends Client {}

Fix issue and add modular ut to cover it in scenarios/clientContext/clientContextWithApiVersion.md.