[Feature] Add Molecular Weight Calculator

[kom-senapati]

Description

The Molecular Weight Calculator simplifies chemistry by computing the total atomic weights of elements in a given chemical formula, helping users swiftly determine the molecular weight of compounds.

Screenshots

Checklist

• [X] I have checked the existing issues.
• [X] I follow Contributing Guidelines of this project.
• [ ] I am a IWOC'24 contributor.
• [ ] I am a JWOC'24 contributor.
• [X] I am a SWOC'24 contributor.

Code of Conduct

• [X] I agree to follow this project's "Code of Conduct".

[Rakesh9100]

Proceed @kom-senapati