Rename int64 timestamp related protobuf fields to <fieldname>NS

[pgporada]

Rename all of int64 timestamp fields to <fieldname>NS to indicate they are Unix nanosecond timestamps.

Part 1 of 4 related to #7060

[pgporada]

The issued field in sa.proto also seems like it should be a google.protobuf.Timestamp.

message AddCertificateRequest {

  // An issued time. When not present the SA defaults to using
  // the current time.
  int64 issued = 4;

[aarongable]

The issued field in sa.proto also seems like it should be a google.protobuf.Timestamp.

Agreed. I wouldn't trust the // Unix timestamp (nanoseconds) comments to be a full accounting of all places where we use an int64 as a timestamp, we've definitely forgotten to include those a time or two. I'd do a survey of all of our .proto files to find any fields we missed.

[beautifulentropy]

This is looking pretty good! I did a quick search through our various *.proto files for int64 fields and turned up a few more candidates.

boulder/ca/proto/ca.proto

Line 44 in c38efd4

int64 revokedAt = 4;

boulder/core/proto/core.proto

Line 52 in c38efd4

int64 revokedDate = 5;

boulder/core/proto/core.proto

Line 54 in c38efd4

int64 lastExpirationNagSent = 7;

boulder/core/proto/core.proto

Line 55 in c38efd4

int64 notAfter = 9;

boulder/core/proto/core.proto

Line 85 in c38efd4

int64 expires = 3;

boulder/core/proto/core.proto

Line 92 in c38efd4

int64 created = 10;

boulder/grpc/test_proto/interceptors_test.proto

Line 11 in c38efd4

int64 time = 1; // In nanoseconds

boulder/sa/proto/sa.proto

Line 210 in c38efd4

int64 issued = 4;

boulder/sa/proto/sa.proto

Line 235 in c38efd4

int64 expires = 2;