feat: add light and dark mode repo banner images

[jbeveland27]

Adds updated banner images with the new logo and also includes light/dark modes.

Preview

The category image below will be displayed in light or dark mode depending on your GitHub settings.

Here's how that preview works (note: this uses images stored in the open-source-office repo just for example, because these images aren't merged into the opensource-website repo yet)

<a href="https://opensource.newrelic.com/oss-category/#community-project">
  <picture>
    <source
      media="(prefers-color-scheme: dark)"
      srcset="https://github.com/newrelic/open-source-office/raw/main/examples/categories/images/dark/Community_Project.png">
    <img
      alt="A New Relic Open Source community project banner. It highlights that this repo is an official New Relic open source community project, supported by a maintainer(s) within New Relic."
      src="https://github.com/newrelic/open-source-office/raw/main/examples/categories/images/Community_Project.png">
  </picture>
</a>

Follow up

~ The copy snippets located in the wiki need to be updated as well to take advantage of the light/dark mode capability~ ~ Update the repolinter rulesets with the new copy snippets~

[gatsby-cloud[bot]]

:white_check_mark: opensource-website-develop deploy preview ready

• Deploy preview
• Build logs · 56s build time
• — View full report

[jbeveland27]

Follow up items have been completed.

• The change to docs/Open-Source-Category-Snippets.md will update the wiki once the docs workflow runs (post-merge).
• The repolinter rulesets are updated in this PR to check for the new copy snippets and the fixes that are raised in the repolinter issue point to this repo's wiki as the common place to find the authoritative copy snippets. I'll merge that PR once this one is merged.

[clarkmcadoo]

hey @jbeveland27, i guess these are meant to be html snippets, can we wrap them in an html code fence?

[nr-opensource-bot]

:tada: This PR is included in version 1.24.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: