feat(Indexes): method generic types for better DX

[ShaMan123]

Description

Add generic types to index read methods for ease of use

Before

const keys = model.getIndexKeys(name) as Uint32Array

After

const keys = model.getIndexKeys<number>(name)

Additional context

#215 needs to be patched with a generic type

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following:

• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Follow the Conventional Commits v1.0.0 standard for PR naming (e.g. feat(examples): add hello-world example).
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[ShaMan123]

ready

[agviegas]

Thanks @ShaMan123! This landed on main in 1d1db70.

Since #215 had already merged and touched the same methods, I rebased your generics on top of it and extended them to the getIndexKey / getIndexValues helpers it added, so the whole index read API is consistent. I also kept getInverseIndexEntry's return type nullable (it returns null in a few runtime paths), and folded in a small fix for a getValues type error.

Closing as merged via squash. Much appreciated!