build.yml: Workflow aligned with nuttx repo

[simbit18]

Summary

This PR modifies NuttX CI and GitHub Actions, to comply with ASF Policy.

According to ASF Policy: We should run at most 15 Concurrent Jobs: https://infra.apache.org/github-actions-policy.html

build.yml: Limit the GitHub Runners
see @lupyuen PR apache/nuttx#13412

added -N -S options

-N Use CMake with Ninja as the backend.
PR apache/nuttx#12721

-S Adds the nxtmpdir folder for storing third-party packages.
PR apache/nuttx#13301

Impact

none

Testing

CI
It complies with ASF Policy: The GitHub Runners did not exceed 15 during the build.

[nuttxpr]

[Experimental Bot, please feedback here]

Yes, this PR appears to meet the NuttX requirements.

Here's why:

• Clear Summary: The summary clearly states the purpose of the change ("Limit the GitHub Runners") and links to the relevant NuttX pull request.
• Minimal Impact: The PR states there is no impact beyond the CI build process itself.
• Testing Addressed: While not providing specific logs, the PR confirms that testing was done within the CI environment, which is appropriate for a change focused on the build system.

Potential Improvements:

• Expanded Testing: While CI testing is great, specifying the tested host and target combinations (even briefly) would strengthen the testing section.
• Impact Details: Even though the impact is minimal, a sentence explaining how the GitHub Runners are being limited would be helpful for reviewers.