Deprecate SearchResult::termMatches()

Deprecate SearchResult::termMatches()

And start indicating that hooks relying on this data might become
unreliable as this data is only populated by SearchDatabase search
engines.

This information was only populated by SearchDatabase implementations
and due to bad initial design of SearchResult[Set] (now fixed) it forced
users of these classes to carry this information for the sole purpose of
highlighting.
Because SearchEngine can now own their SearchResult[Set] implementations
nothing that is engine specific should be exposed outside of these
specific implementations.
If there are some logic that still requires access to such list of terms
they should be made engine specific by guarding their code against
instanceof SqlSearchResult.

Change-Id: I38b82c5e4c35309ee447edc3ded60ca6a18b247a
Depends-On: I53fe37c65c7940f696c1e184125e01e592a976e4