Generates a Flex Microform context token. Required to securely collect card details on the partner's front end — card data never touches partner servers.Pass the returned captureContext to the Flex Microform SDK in the browser. The SDK tokenises the card number and returns a transient token for subsequent payment calls.Supported cardNetworks: VISA, MASTERCARD, AMEX, DISCOVER, CARNET, CARTESBANCAIRES, CUP, DINERSCLUB, EFTPOS, ELO, JCB, JCREW, MADA, MAESTRO, MEEZA