fix: Serialization docs

[EmandM]

Purpose of this PR

• Adds detail and cross-linking around the serialization docs
• Moves some docs into the tests and use code embeds to embed the tested code into the docs
• Deletes the duplicated Custom NetworkVariable section from the NetworkVariable docs
• Adds a small section about delta updates to the NetworkVariable docs

Jira ticket

UUM-137288
fixes: #2994

Changelog

• Fixed: UserNetworkVariableSerialization<T>.DuplicateValue is now able to be used anywhere UserNetworkVariableSerialization<T>.ReadDelta and UserNetworkVariableSerialization<T>.WriteDelta can be used.
• Changed: Updated the serialization docs.

Documentation

• Includes documentation for previously-undocumented public API entry points.
• Includes edits to existing public API documentation.

Testing & QA (How your changes can be verified during release Playtest)

Functional Testing

Manual testing :

• Manual testing done

Automated tests:

• Covered by existing automated tests
• Covered by new automated tests

Does the change require QA team to:

• Review automated tests?
• Execute manual tests?
• Provide feedback about the PR?

If any boxes above are checked the QA team will be automatically added as a PR reviewer.

Backports

n/a

[jabbacakes]

If you can give me a giant PR, I can give you a giant pile of suggestions. Seems fair 😂

No major notes - this is a great improvement of the serialization docs. So many links 😍 Most of my comments are just wording tweaks, changed the title of a page in a couple of instances to make it clearer what you can actually do with a certain interface at a glance.

[jabbacakes]

If you can give me a giant PR, I can give you a giant pile of suggestions. Seems fair 😂

No major notes - this is a great improvement of the serialization docs. So many links 😍 Most of my comments are just wording tweaks, changed the title of a page in a couple of instances to make it clearer what you can actually do with a certain interface at a glance.

[NoelStephensUnity]

Beautiful!