fix: #1436: load custom level should set correct language

[sebp999]

Description

Bug fix for #1436 : the language (Blockly/Python/both) not being set correctly when a custom level is loaded

How Has This Been Tested?

• Added a test that the data is saved correctly.
• Ran unit and end-to-end tests

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• [ x ] I have linked this PR to a ZenHub Issue.

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This change is 

[faucomte97]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @sebp999)

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game/tests/test_level_editor.py line 336 at r1 (raw file):

        assert new_level.pythonViewEnabled is True
        assert new_level.pythonEnabled is False
        assert new_level.blocklyEnabled is True

Let's just have assert x for True and assert not x for False, no need to specify them at the end 🙂

Code quote:

        assert new_level.pythonViewEnabled is True
        assert new_level.pythonEnabled is False
        assert new_level.blocklyEnabled is True

[faucomte97]

Reviewed 4 of 4 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @sebp999)