feat: new mux quickstart

[jcountsNR]

Summary

New Mux quickstart. Includes Dashboard, data source, and quickstart files. Creating as a draft until the docs are published.

Pre merge checklist

• Did you check you NRQL syntax? - Does it work?
• Did you include a Data source and Documentation reference?
• Are all documentation links publicly accessible?
• Did you check your descriptive content for voice and tone?
• Did you check your descriptive content for spelling and grammar errors?
• Did you review your content with a subject matter expert? (e.g. a Browser agent quickstart is reviewed with a member of the Browser Agent team)

Dashboards

• Does the PR contain a screenshot for each of your dashboards?
• Do your screenshots show data?
• Has the sanitization script been run on each dashboard?

Alerts

• Did you check that your alerts actually work?

[github-actions]

Thank you for your contribution, our team will be reviewing this shortly, please be available for any follow up questions or code review feedback!

[github-actions]

Click the link(s) below to view a preview of your changes on newrelic.com/instant-observability

- mux-video
- golang/mux

[jcountsNR]

@aswanson-nr has this been merged yet? I'm thinking we should hold off for just a bit, I got some feedback from Mux and they want to make a few changes to the dashboard and text here.

[github-actions]

Old PRs will be closed after 30 days of inactivity. This PR has been quiet for 14 days and is being marked as stale. Reply here to keep this PR open.

[aswanson-nr]

Not stale! going to remove that label.
@jcountsNR this appears to be ready to go, but there's a test.json dashboard. If that's intended to be part of this quickstart, could adjust the name to be more descriptive?

[github-actions]

Old PRs will be closed after 30 days of inactivity. This PR has been quiet for 14 days and is being marked as stale. Reply here to keep this PR open.

[brammerl]

Removing the stale logo. Waiting on JRCounts to get clearance before publishing.

[github-actions]

Old PRs will be closed after 30 days of inactivity. This PR has been quiet for 14 days and is being marked as stale. Reply here to keep this PR open.

[jcountsNR]

@aswanson-nr / @seemantk - Updating this one. It should be ready to be reviewed in the next cycle!