User can't use operational failure rate if it is missing in the data

[kostobog]

Operational failure rate cannot be used if it is not present in the data.

Tasks:

• Open access to failure rate api in analytics server module - resolved in kbss-cvut/ava-analytics#39
• Fix SNS export - add general fault event types (not related to aircraft) kbss-cvut/23ava-distribution#129
• Fix fault tree editor does not work as expected after failure rate is updated #533 - Make sure supertypes is array #534

[blcham]

Currently this was done by workaround -- https://github.com/kbss-cvut/ava-analytics/pull/39, which should be properly fixed in #532.

[blcham]

@kostobog so does it work now ?