Monitoring enhancement
- add selection how often get is done (max freq once / minute, upto 60 minutes)
- add a feature where user is notified via email if get operations fail 3 times in a row see also issue #3732 - this can be implemented also
so, after user has ticked the tickbox; following ui should be shown

tests: #1 user ticks "Enable API Monitoring" expected: New selections are show, like in image in this issues #2 after test#1 user toggles between different Endpoints expected: radio selection changes #3 user sets value 1 to "check every.." selection user sets value 1 to "alert if checks fail.." selection user hits save expected: there is a entry in monitoring table. If you navigate to that API, "API is operating normally" text is shown #4 user hits save after step 3 expected: new entry appears to the table after a while #5 user enters non-existing url and hits save expected: after a while, entry appears stating that API is not working properly. "API is operating normally" text is changed to error code. Additionally when time goes by and test fail given time, user receives email notification, where the Subject is "API health problem" and Body is
"You have enable monitoring, API
Get better soon,
APInf staff " #6 user unticks "Enable API Monitoring" expected: no emails are sent. table containing entries disappear. "API is operating normally" text is not shown
additional : show data as calendar? also, show uptime in % somewhere for API users