Add a toy indoor scenario for Danang hospital

[minhduc0711]

Based on the building model (https://github.com/COMOKIT/COMOKIT-Model/tree/comokit-building), this PR adds a toy model to simulate indoor interactions in the nephrology department of Danang hospital. The model can be extended for multiple floors.

This PR also introduces new abstract entities (for Building, Individual and Activity), which might break other models because I was not really confident when merging new changes.

Demo (two floors with the same exact floor plans; yellow rooms are elevators/stairways)

https://user-images.githubusercontent.com/34294427/151791199-b0230807-7577-4aa6-9995-c9dcac0e21ec.mp4

A few possible TODOs:

• Time step must be set to 1#s due to the requirement of pedestrian skill, so the model feels really slow
• Improve stairs & elevator
  • Make agents exit the correct corresponding stairway/elevator
  • Make agents wait before they can can reach another floor
• More detailed agendas
• CRS problems when using actual different floors