Fix Particle Definition Conflicts

[APickledWalrus]

Description

This PR aims to fix some particle-itemtype conflicts that were introduced in #6716

For example, some inputs such as totem of undying would parse as a visual effect rather than an itemtype. This caused errors with variables as visual effect serialization is broken. To combat this, I've made it so that visual effects are parsed after item types. Additionally, I've added some additional optional keywords to the affected particle definitions.

We might also prefer a more aggressive route of requiring the usage of keywords like particle. I wanted to avoid this if possible. We may choose to pursue this if the parse-order changes reveal any unexpected issues.

There is one breaking change that affects the elder guardian option that was added in 2.8.5. It now requires particle. I attempted to force visual effect parsing after entity types/data, but that caused unexpected test failures.

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Target Minecraft Versions: any
Requirements: none
Related Issues: #6774

[sovdeeth]

Can we get a specific regression test for this?
also, re: requiring particle, that's likely what I'm going to do with particle rework (each particle/effect would have "particle", "effect", or "sound" as part of its pattern to help avoid ambiguity, depending on what it is)