Add GetObjectDirectorySize RPC

This RPC will be used to determine if a push will
exceed the size limit of a repository.
4 jobs for pb-get-object-directory-size-1-27 in 1 minute and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #234501643
build

00:01:06

passed #234501644
check-grpc-proto-clients

00:01:04

passed #234501645
danger-review

00:01:41

passed #234501642
test

00:01:42