Improvements in the cell division demo

[vasvav]

This PR concerns fixing and improving the demo that demonstrates the division of agents (representing biological cells in this example).

• highlighted the use of the pertinent model parameters for cell division, e.g., growth rate and maximum cell diameter to signal division;
• added the corresponding input parameter file that is usually represented by a "bdm.toml" file;
• provided a new demo, called as cell_division_enhanced, which builds on the existing cell_division one while it adds a bit more complexity to it by adding a user-defined "cell" type that has a dedicated way of multiplying (i.e., cell division).
• added ReadMe files that outline each demo - they provide important guidance how to run the demos and what to expect in the end.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[TobiasDuswald]

I'd rename ReadMe.md to README.md for consistency across the code base. Very much like the idea of having a README. Are they copied with the bdm demo cell-division command?

[TobiasDuswald]

@UmarAbubacar @sportokalidis 🔔 can you review this ?