Interoperability: Submit days since onset of symptoms, Add 15th key to transmission risk vector (EXPOSUREAPP-2748, EXPOSUREAPP-2686) (#1223)

* Update proto file to generate TemporaryExposureKey and fix visibility

* Introduce placeholder and model for days since onset of symptoms

* EXPOSURE_APP_2686 (wip)

* fixed annotation

* fixed compile error

* Implement determinator for days since onset of symptoms in accordance with the risk vector determinator

* extracted index calc

* add 15th key

* get index

* Reverse order of days since onset of symptoms vector to align index with risk vector

* updated behaviour

* fixed today

* - false thinking

* implemented days ago

* detekt + ktlint

* not needed

* fixed index into vectors

* https://github.com/corona-warn-app/cwa-app-android/pull/1223#discussion_r494957683



* tests

* Move vector length to determinator and fix test

* Fix test and ktlint

* improvements suggested in PR

* use UTC, improved tests

* tests with gap and several keys in one day

* more unit tests + fixed a bug in age of days

* test transmission risk vector

* Improve test readabilty and switch to Junit5

* inject it

* End of class please.

* fixed tests

* remove magic number

* fixed tests

* fixed test

* fixed test

* Fix lint issues

* Add java doc with link to the documentation.

* Fix tests

* fixed test

* ktlint

Co-authored-by: ralfgehrer <mail@ralfgehrer.com>
Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>
Co-authored-by: Matthias Urhahn <matthias.urhahn@sap.com>