pgv: validation support for Bootstrap/xDS/filters. (envoyproxy#2146)

This patch lands checking via https://github.com/lyft/protoc-gen-validate in Envoy for bootstrap, xDS ingestion and during filter instantiation.

Risk Level: Medium (things might start blowing up on config ingestion that were slipping through before).
Testing: Mostly negative tests for bootstrap/xDS/filters, since the happy path is already validated through the existing test suite.

Signed-off-by: Harvey Tuch <[email protected]>

data-plane-api: bump sha (envoyproxy#2057)

For new doc stuff.

Signed-off-by: Matt Klein <[email protected]>

docs: mov tag guard to release build (envoyproxy#2056)

Signed-off-by: Matt Klein <[email protected]>

docs: push on tags only (envoyproxy#2055)

Fixes envoyproxy#1290

Signed-off-by: Matt Klein <[email protected]>

Fixes to Dockerhub release tagging (envoyproxy#1777)

Signed-off-by: bndw <[email protected]>

optional: make coverity happy (envoyproxy#1767)

Signed-off-by: Matt Klein <[email protected]>

Using common member variables in integration tests (envoyproxy#1532)

docs: 1.3.0 release notes (envoyproxy#926)

Envoy Rate Limit: Enable stage setting matching. (envoyproxy#532)

docs: 1.1.0 release notes (envoyproxy#259)