CSD: notify when RS2 momentary exposure is reached

RS2 is defined in IEC 62368-1 3rd edition as 100dBA. Added however the
possibility to further restrict this value as part of the momentary
exposure API.

Test: UT and manual tests
Bug: 256616352
Change-Id: I004a620e5e7915824d390f7ddc41c16f9675d45a