Integrate latest FEAScript-core features

[nikoscham]

This issue is part of the FEAScript roadmap for the upcoming 0.2.0 release (https://github.com/orgs/FEAScript/discussions/17).

Tasks

• Update import paths to use the ESM version of FEAScript
• Integrate web workers functionality to offload heavy computations from the main thread (see the tutorial https://github.com/FEAScript/FEAScript-website/blob/main/tutorials/HeatConduction2DFinWorker.html)
• Integrate .msh (Gmsh) mesh importing (see the tutorial https://github.com/FEAScript/FEAScript-website/blob/main/tutorials/HeatConduction2DFinGmsh.html)