feat: add lerp function

[aleclarson]

Tip

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Summary

Introduce the lerp function for linear interpolation, a common need in frontend JavaScript. This function will be used in the upcoming color-mixing PR.

Questions

1. Does this fit in Radashi?
   I believe it does. In my years as a frontend dev, I've written my own lerp countless times. It's small enough to not be a big deal for Node.js applications using Radashi.
2. Should it have a better name?
   I settled on lerp since it's the most commonly used name for such a function. I included an "Etymology" section in the docs to hopefully clear up any confusion.

For any code change,

• Related documentation has been updated, if needed
• Related tests have been added or updated, if needed
• Related benchmarks have been added or updated, if needed

Does this PR introduce a breaking change?

No

[adamhamlin]

I like the etymology section 👍

[github-actions]

A new beta version 12.2.0-beta.ef0154b has been published to NPM. 🚀

To install:

pnpm add [email protected]

The radashi@beta tag also includes this PR.