This is the OSS portion of enterprise PR 2339.
It improves our handling of "irrecoverable" errors in proxycfg data sources.
The canonical example of this is what happens when the ACL token presented by
Envoy is deleted/revoked. Previously, the stream would get "stuck" until the
xDS server re-checked the token (after 5 minutes) and terminated the stream.
Materializers would also sit burning resources retrying something that could
never succeed.
Now, it is possible for data sources to mark errors as "terminal" which causes
the xDS stream to be closed immediately. Similarly, the submatview.Store will
evict materializers when it observes they have encountered such an error.
This is the OSS portion of enterprise PR 2157.
It builds on the local blocking query work in #13438 to implement the
proxycfg.IntentionUpstreams interface using server-local data.
Also moves the ACL filtering logic from agent/consul into the acl/filter
package so that it can be reused here.
Daniel Upton