Simplify build process by auto-installing npm packages and simplify the contributor guide (#1799)

* Clarify some of the contributing building instructions

* Bump wasm-bindgen version

* Simplify build process and improve docs

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Co-authored-by: Keavon Chambers <keavon@keavon.com>

.devcontainer/devcontainer.json

@@ -7,7 +7,6 @@
 		"ghcr.io/devcontainers/features/node:1": {}
 	},
 	"onCreateCommand": "cargo install cargo-watch cargo-about",
-	"postCreateCommand": "cd frontend && npm install",
 	"customizations": {
 		"vscode": {
 			// NOTE: Keep this in sync with `.vscode/extensions.json`