Prior to this PR if a domain was an exact match to a public suffix
list entry the certificates per name rate limit was applied based on the
count of certificates issued for that exact name and all of its
subdomains.
This PR introduces an exception such that exact public suffix
matches correctly have the certificate per name rate limit applied based
on only exact name matches.
In order to accomplish this a new RPC is added to the SA
`CountCertificatesByExactNames`. This operates similar to the existing
`CountCertificatesByNames` but does *not* include subdomains in the
count, only exact matches to the names provided. The usage of this new
RPC is feature flag gated behind the "CountCertificatesExact" feature flag.
The RA unit tests are updated to test the new code paths both with and
without the feature flag enabled.
Resolves#2681
1ed34a4a5d