This integrates Rust exposure suggestions with desktop. Exposure suggestions are
a part of the replacement for the existing potential exposures feature
(bug 1881875). When we want to test potential exposures in the future, we can
add new exposure suggestions to remote settings and tell the Rust component to
ingest them and return them in queries. When the Rust component returns an
exposure suggestion, desktop will record it in exposure telemetry. (The other
part of the replacement is keyword exposure telemetry in bug 1915507 D220501).
More details about the design of exposure suggestions here:
* Bug 1893086
* https://github.com/mozilla/application-services/pull/6343
The way desktop tells the Rust component about different types of exposure
suggestions is through the new "provider constraints" feature. `ingest()` and
`query()` can take a `SuggestionProviderConstraints` object that changes what's
ingested and queried. Therefore, we need to re-ingest exposure suggestions when
the provider constraints change. Right now, exposure suggestions are the only
kind of suggestions that use provider constraints.
Depends on D220359
Differential Revision: https://phabricator.services.mozilla.com/D220359
247ce81e9b