[BETA] Create a DBaaS ClickHouse user

Request

• Base URL
  https://api-ch-gva-2.exoscale.com/v2
• Auth
  none declared
• TypeScript
  https://skmtc.dev/exoscale/apis/exoscale-api/docs/dbaas-clickhouse/:service-name/user/post.ts

  A function with typed inputs. Its response is checked against the schema.