ENH: Insert apogee state into solution list during flight simulation

[Gui-FernandesBR]

Pull request type

• [x] Code changes (bugfix, features)

Checklist

• [x] Tests for the changes have been added (if needed)
• [x] Docs have been reviewed and added / updated
• [x] Lint (black rocketpy/ tests/) has passed locally
• [x] All tests (pytest tests -m slow --runslow) have passed locally
• [x] CHANGELOG.md has been updated (if relevant)

Current behavior

Recently reported on discord:

New behavior

The problem was related to Function interpolations. I added the apogee state to the state solution so it created a point at the minimum value of the free stream speed curve (i.e. the apogee). This way we reduced the error when evaluating the stream speed at apogee.

Breaking change

• [x] No

[codecov[bot]]

Codecov Report

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

Project coverage is 75.71%. Comparing base (655f4be) to head (673ac84). Report is 1 commits behind head on develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #638 +/- ## ======================================== Coverage 75.70% 75.71% ======================================== Files 81 81 Lines 9813 9815 +2 ======================================== + Hits 7429 7431 +2 Misses 2384 2384 ```

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