refactor: replace deprecated grpc packages

[romshark]

• replace deprecated github.com/golang/protobuf with google.golang.org/protobuf
• replace deprecated ptypes.TimestampProto from github.com/golang/protobuf/ptypes with google.golang.org/protobuf/types/known/timestamppb
• replace deprecated grpc.WithInsecure() with google.golang.org/grpc/credentials/insecure

Deprecation notice: https://pkg.go.dev/github.com/golang/protobuf

[jiceatscion]

This change is 

[jiceatscion]

As before... I should not approve as sole reviewer. But this sounds good. Besides my question regarding unix time. Add the change of timestamp pb to the description?

Reviewed 14 of 14 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @oncilla and @romshark)

[oncilla]

Reviewed 12 of 14 files at r1, 10 of 10 files at r2, 1 of 1 files at r3, 1 of 1 files at r4, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @jiceatscion)

[jiceatscion]

Reviewed all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @romshark)