Equations. Added only ns and Euler eqations to pull request and added examples to both eqations only tessellation (split of this pull request https://github.com/NVIDIA/modulus-sym/pull/30)

[chaous]

Modulus Pull Request

Description

Checklist

• [ ] I am familiar with the Contributing Guidelines.
• [ ] New or existing tests cover these changes.
• [ ] The documentation is up to date with these changes.
• [ ] The CHANGELOG.md is up to date with these changes.
• [ ] An issue is linked to this pull request.

Dependencies