feat: Rationalize Equipment Category Schema

[mpeck451]

What does this do?

1. Adds a new "equipment_categories" array for all items within the "5e-SRD-Equipment.json" file.
2. Creates a new script for category validation in src/tests.
3. Adds "Donkey" and "Camel" to "5e-SRD-Equipment-Categories.json". (Previously missing)
4. Adds "standard-gear" to ammunition items in "5e-SRD-Equipment.json". (Present in "5e-SRD-Equipment-Categories.json", but missing in "5e-SRD-Equipment.json")
5. Adds "land-vehicles" category to land vehicles in "5e-SRD-Equipment.json" (Present in "5e-SRD-Equipment-Categories.json", but missing in "5e-SRD-Equipment.json")

How was it tested?

I created a new script in src/tests that validates categories and items between "5e-SRD-Equipment-Categories.json" and "5e-SRD-Equipment.json". This ensures that all items categories in "5e-SRD-Equipment.json" are present in "5e-SRD-Equipment-Categories.json". It also ensures that all category items in "5e-SRD-Equipment-Categories.json" are present in "5e-SRD-Equipment.json". Using this method, I found that "Donkey" and "Camel" were both missing from "5e-SRD-Equipment-Categories.json". I also found that 'standard-gear' was missing from ammunition items in "5e-SRD-Equipment.json". I also found that there was no reference to the "land-vehicles" category for land vehicles in "5e-SRD-Equipment.json".

Is there a Github issue this is resolving?

Yes., issue #397 - Equipment category schema rationalization

Did you update the docs in the API? Please link an associated PR if applicable.

No.

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