[NOREF] Show MTO matrix if started

[patrickseguraoddball]

NOREF

Description

Previously MTO matrix was hidden if there were no milestones added. The util in this PR will check if any categories or subcategories have been created as criteria for rendering the MTO matrix - even in the absence of any milestones. This util will also not count Uncategorized as categories/subcategories.

Additionally added a custom apollo cache key and removed toggle icon if no children present

Caution

We have not yet hooked up a refetch on the form mutations, so you will need to refresh or force rerender in the app to see changes take effect.

How to test this change

1. Create a model plan and go to matrix
2. Verify empty state
3. Added a category and refresh
4. Verify matrix renders
5. Repeat but this time add a milestone
6. Verify matrix renders

PR Author Checklist

• I have provided a detailed description of the changes in this PR.
• I have provided clear instructions on how to test the changes in this PR.
• I have updated tests or written new tests as appropriate in this PR.
• Updated the Postman Collection if necessary.

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[ClayBenson94]

Works as expected! Thanks @patrickseguraoddball!

[garyjzhao]

LGTM! Category and Milestones are rendering on the table