Add CODEOWNERS file

[adamyeats]

No description provided.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[aangelisc]

Tagging the following squads for visibility:
@grafana/aws-datasources
@grafana/enterprise-datasources
@grafana/oss-big-tent

[sarahzinger]

I like this, just want to confirm, this doesn't mean changes are blocked by having all squads review yeah? If one reviewer approves on behalf of the squad and the rest are optional to review, is that "enough"? I think probably? Just wanted to double check we're not setting something where we have to have a reviewer from every squad before it's able to be merged (which is arguably reasonable, but I think maybe a bit much?)

[gabor]

LGTM 👍

[aangelisc]

@sarahzinger yep we definitely don't want to block, a review from a single codeowner should be sufficient 😊