Fix toggle terminal visibility

[SeanHersh]

Description of What Happened:
In my open-source contribution, I aimed to fix a bug where the "Toggle Terminal" button stayed visible even when the terminal was set to be hidden in the metadata. After investigating, I realized that key parts of the metadata handling function were missing from the repository I pulled from.

I added a terminal property to the part schema as a boolean flag to address this. This flag controls whether the terminal should be shown or hidden for each tutorial part. While I couldn't fully verify the solution due to missing parts in the repository, I contributed this schema change as a potential fix to help manage terminal visibility.

Additions Made:

Added terminal property to the part schema to control terminal visibility for each part.
Introduced logic based on this flag to toggle the terminal visibility in the interface.

All added components have been commented out with a full description of functionality and purpose

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[AriPerkkio]

Thanks for the PR @SeanHersh!

However these changes don't look right to me. This bug fix should not require any changes in how metadata is configured. We'll also need test cases that verify the fix in order to accept PRs for this.

It also seems that this issue might already be working just fine: #300 (comment).