feat(http): refactor and improvements

.changes/http-multipart-refactor.md

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+---
+"http-js": minor
+---
+
+Multipart requests are now handled in JavaScript by the `Request` JavaScript class so you just need to use a `FormData` body and not set the content-type header to `multipart/form-data`. `application/x-www-form-urlencoded` requests must be done manually.

.changes/http-plugin-refactor.md

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+---
+"http": minor
+"http-js": minor
+---
+
+The http plugin has been rewritten from scratch and now only exposes a `fetch` function in Javascript and Re-exports `reqwest` crate in Rust. The new `fetch` method tries to be as close and compliant to the `fetch` Web API as possible.