Add wear_keep to datalayer-helper-guide and sample

[oas004]

WHAT

Add wear_keep.xml to data layer helper guide and sample

From what I understand from https://issuetracker.google.com/issues/348688201#comment4 that is what we needed for resource shrinker to work. I'm not 100% sure so all feedback is more than welcome on that.

WHY

resolves #2281

HOW

Add wear_keep.xml to data layer helper guide and sample

Checklist 📋

• Add explicit visibility modifier and explicit return types for public declarations
• Run spotless check
• Run tests
• Update metalava's signature text files

[yschimke]

cc @kul3r4 FYI

[kul3r4]

Shall I also change https://github.com/android/wear-os-samples/blob/main/DataLayer/Wearable/src/main/res/values/wear.xml?

[yschimke]

@oas004 Good catch by Chiara, can you update that also in this PR? Thanks for your patience with changes bouncing back and forth.

[oas004]

@oas004 Good catch by Chiara, can you update that also in this PR? Thanks for your patience with changes bouncing back and forth.

No worries at all! Thank you for thorough reviews! 🙌 The change that she is referring to isn't that in wear-os sample repository? I can update that as well, but I'm not sure it is possible in this PR? Maybe I'm misunderstanding something?

[kul3r4]

No worries at all! Thank you for thorough reviews! 🙌 The change that she is referring to isn't that in wear-os sample repository? I can update that as well, but I'm not sure it is possible in this PR? Maybe I'm misunderstanding something?

Yes it's a different repository, happy to review if you want to send a PR there.

[yschimke]

@oas004 @kul3r4 oooofffff, sorry. How do I git?!?!?!