chore(EMS-4155): apim notify integration

[ttbarnes]

Introduction ✏️

• APIM has been updated so that file buffers can be sent to Notify.
• EXIPS can therefore now call APIM to send emails, instead of calling Notify directly.

Resolution ✔️

• Create new sendEmail APIM integration function.
• Update relevant helper functions.
• Remove notifications-node-client NPM dependency.
• Create new types.

Miscellaneous ➕

• Various documentation improvements.
• Improve some API error handling unit tests.

[abhi-markan]

Apologies for the confusion, I meant it will be wise to do following to keep the code DRY?

const isValidResponse = response.data && validateStatus(response.status);

if(isValidResponse) {...

The function is Axios call can be centralised.

 const validateStatus = (status) => {
          const acceptableStatus = [201];
          return acceptableStatus.includes(status);
        },