SM: SecurityRecordDatabase updates

Convert the underlying structure of the SRD from a vector to a set.
Hand out shared_ptr to record.

Bug: 159054611
Test: cert/run --verbose --speed-hax --host --test_filter=SecurityTest
Test: cert/run --verbose --speed-hax --host --test_filter=LeSecurityTest
Tag: #gd-refactor
Change-Id: Ia86f00bcf897866a9b1e95f7fd4f447912436218