Use native concurrency functionality and separate CI and PR actions

[maxxboehme]

What does this Pull Request accomplish?

Migrate to using the native concurrency functionality provided by github actions. This migration was suggested by the styfle/cancel-workflow-action we were using in their README.

Also created a separate ci.yml and pr.yml for easier sorting when looking at the actions tab. This also mimics what other projects like nidaqmx-python and measurement-plugin-labview follow. This also makes it clear on the rules that for PR builds if another action is kicked off it would cancel the previous while the same is not true for CI builds.

Why should this Pull Request be merged?

• Clear division of CI and PR builds
• Migrate to using native github action functionality for canceling multiple PR jobs running at once for the same PR.

What testing has been done?

PR build

[reckenro]

Looks good to me. When you're ready to submit you'll need to change main branch's protection policies to switch over the required checks to the new ones.

[maxxboehme]

Updated required checks for both "main" and "releases" branches.