Feature/juvenile dispersal - Adding juvenile dispersal to the Animal Module

[TaranRallings]

Description

Following Madingley, this builds on previous starvation-induced dispersal to add a dispersal check immediately after a cohort is born. When migrate_community is called during the normal flow of model execution there is a secondary check to see if the cohort is newly created. If the cohort is new, it creates a probability of dispersal based on allometric movement speed and grid size.

Currently, this only works for 'rook move' dispersal. The logic can be expanded for diagonal movement and multi-grid occupancy but we can leave that for a little later.

Fixes # (issue)

Type of change

• [x] New feature (non-breaking change which adds functionality)
• [ ] Optimization (back-end change that speeds up the code)
• [ ] Bug fix (non-breaking change which fixes an issue)

Key checklist

• [x] Make sure you've run the pre-commit checks: $ pre-commit run -a
• [x] All tests pass: $ poetry run pytest

Further checks

• [x] Code is commented, particularly in hard-to-understand areas
• [x] Tests added that prove fix is effective or that feature works

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.62%. Comparing base (88a6de3) to head (af0f340).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #419 +/- ## =========================================== + Coverage 94.59% 94.62% +0.02% =========================================== Files 69 69 Lines 3648 3666 +18 =========================================== + Hits 3451 3469 +18 Misses 197 197 ```

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