Merge branch 'master' into new_tsi

etc/roots.pem

src/core/lib/http/httpcli_security_connector.c

src/core/lib/security/transport/security_connector.c

src/core/tsi/ssl_transport_security.c

src/core/tsi/ssl_transport_security.h

...ckerfile/grpc_clang_format/clang_format_all_the_things.sh