Add Doppler integration (ECOINT-6)

[nmanoogian]

What does this PR do?

This PR creates the Doppler log collection integration. This is an API-based integration that uses OAuth to connect Doppler with Datadog. Once connected, Doppler will begin sending activity log data to Datadog.

Motivation

What inspired you to submit this pull request?

Review checklist

• PR has a meaningful title or PR has the no-changelog label attached
• Feature or bugfix has tests (Not Relevant)
• Git history is clean
• If PR impacts documentation, docs team has been notified or an issue has been opened on the documentation repo
• If this PR includes a log pipeline, please add a description describing the remappers and processors.

[neko-dd]

Created DOCS-8635 for docs review

[michaelcretzman]

Approved with some minor edits.

[nmanoogian]

Thanks all for the feedback!

A question for you: Do I need the files added in the "WIP: Add tests" commit? I re-ran ddev create and noticed that these came up.

I still need to let CI run and collect the test log results. I'll push again once that's done.

[nmanoogian]

Another question: What should I provide for these manifest values if our integration doesn't produce metrics or provide service checks:

{
  "assets": {
    "integration": {
      "metrics": {
        "prefix": [
          "Missing data for required field."
        ],
        "metadata_path": [
          "Missing data for required field."
        ]
      },
      "service_checks": {
        "metadata_path": [
          "Missing data for required field."
        ]
      }
    }
  }
}

[london-wharton]

Left a suggestion to update the Oauth client id. I believe this should fix the failing validations!

[london-wharton]

lgtm. Thanks for making that change!