Outlook gCal integration fix (fix included)

[Valentina R]

Events created in Outlook (gCal integration) sync to gCal but not to BookingWP. The issue is the length of the calendar event ID created in Outlook. The length is 181 characters but the DB column event_id that stores the availability rules allows 100 chars. Changing that to 200 chars fixes it. Reported here.

[Željan Topić]

Added with 4.18.1, applies to new installs

[Valentina R]

@Željan Topić can it be fixed for existing installs as well?

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