Publish data as Salesforce platform event

[jwtruver]

Use the Salesforce Pub/Sub API to push an array of per-contact data to the platform event. Get data from endpoint in #510 .

[{
	contactId: ‘0032g00000UtKcCAAV’,
	personId: ‘1235’,
	volgisticsId: 1235,
	updatedVolunteerStatus: ‘Active’,
	updatedFirstVolunteerDate: 2021/01/01,
	updatedLastVolunteerDate: 2021/02/02,
	updatedFosterStartDate: 2020/10/18,
	updatedFosterEndDate: 2022/01/01
}]

[kfettich]

The following fields need to be written into SalesForce:

• person IDs from external sources (volgistics & shelterluv, if available)
• Volunteer status (from Volgistics data, "Master" tab, "Status" field; "Applicant" value will be converted to "New Sign Up" before getting written into SF)
• Foster status (TBD)
• Foster start date: the first time they ever took in a foster animal; if the field is already filled in SalesForce, do not overwrite
• Foster end date: the date when the last foster was returned

[kfettich]

If writing to SF fails, we also want to print an informative error message so maintenance folks know what to do if it fails