refactor(deps): Remove `extend` dependency

[danielbankhead]

Remove extend & @types/extend dependencies in favor of native, standardized dependencies.

[ddelgrosso1]

There are several places in the code that we utilize the deep option to extend (example here). While the shallow cases could be replaced by Object.assign the deep cases would require us to either roll our own recursive option, leave extend in place, or remove in favor or something like lodash.

[danielbankhead]

Here are a few options worth exploring:

• https://developer.mozilla.org/en-US/docs/Glossary/Deep_copy
• https://developer.mozilla.org/en-US/docs/Web/API/structuredClone