Migrate library for improved Deno support

[aaronhuggins]

In preparation for some Deno prod work in a private project, I'm prepping for a v1.0 release. The goal is to heavily simplify the codebase, improve the deployment process, and reduce load to maintain the library.

• [x] Release v0.4.0 on npm #10
• [x] Merge all outstanding PRs #13
• [x] Use inclusive branch naming, i.e. main
• [x] Remove all node-specific configuration
• [x] Clean up codebase for vanilla Deno support #15
• [x] Add Deno test suite
• [x] Add support for encoding numeric keys in maps #16
• [x] Add Deno config
• [x] Add support for Deno to Node Tool
• [x] Forbid duplicate map keys during decoding #11
• [x] Add Github CI/CD pipeline
• [x] Deploy v1 to Deno.Land/x and NPM #17

[aaronhuggins]

For interested parties, here's how the docs are shaping up.

Though the docs will be generated via doc.deno.land, they are applicable to Node/Deno/Web since it's literally all the same code.