Introduce default traits

[madsodgaard]

Follows up on the discussion in #1993 and introduces the traits:

• BinaryDelimitedStreams
• FieldMaskSupport

[thomasvl]

Looking back at #1505, I believe PathDecoder, PathVisitor, and Message+FieldMask.swift should probably also get gated.

Is there a good way to test with each of these disable to confirm we've got things properly gated?

[thomasvl]

Is there a good way to test with each of these disable to confirm we've got things properly gated?

Any suggestions for this part so we don't accidentally break these?

[FranzBusch]

Any suggestions for this part so we don't accidentally break these?

We can setup CI that tests with no traits or other trait combinations if we want to.

[thomasvl]

Any suggestions for this part so we don't accidentally break these?

We can setup CI that tests with no traits or other trait combinations if we want to.

That seems like it might be worth while. And maybe adding something to make check that checks without them. Is there something we can reference to setting this up? I'm guessing it can land after the fact.

[madsodgaard]

@thomasvl I extended CI to test the different combinations of traits, let me know if this is suitable 👍

[thomasvl]

@FranzBusch how's this looking to you? Since you have more experience with traits.

[FranzBusch]

This LGTM to me besides this minor nit. If @thomasvl and @allevato are good with this being the only default trait to exist until a next major then I am good with moving forward here.

[allevato]

If @thomasvl and @allevato are good with this being the only default trait to exist until a next major then I am good with moving forward here.

LGTM. Nothing else immediately jumps out at me as something we might want to be able to disable for the time being.

[thomasvl]

Nothing else comes to mind.

[thomasvl]

@FranzBusch someone will need to update the expected checks before this can land. And do you want semver/minor on this?

[FranzBusch]

Updated the checks and added minor to indicate the introduction of the default trait