sanitize calendar event tooltip text
sanitize calendar event tooltip text

fixes LS-3470
flag=wrap_calendar_event_titles

test plan:
  - ensure the wrap_calendar_event_titles flag is enabled
  - navigate to your calendar
  - create an event with the title of:
    <script>alert("oh noes")</script>
  - from the month view, hover over the event
    - a tooltip with a single line of the title should appear

qa risk: low

Change-Id: I4314255182c45d7880e9184b31c11264ad481208
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/300507
Reviewed-by: Luis Oliveira <4ec7209c0a6350a2c3877fe0e8e120f972fc692a@instructure.com>
QA-Review: Luis Oliveira <4ec7209c0a6350a2c3877fe0e8e120f972fc692a@instructure.com>
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Product-Review: Davis Hyer <60fbffed049dcae9186e63e354cbc0b825bf5523@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms