Add per-method convenience wrappers (http_get, http_post, …)

Add thin static wrappers over `request()`/`request_raw()` so common calls drop the positional boilerplate (`request(url, PackedStringArray(), Method.GET, "", opts)` → `http_get(url)`).

- One method per HTTP verb; each delegates to `request()`/`request_raw()` so redirects, SSE, cancellation, and progress come along for free.
- Prefer flat optional params over an `Options` subclass — keep a single `Options` type, with `headers`/`body` as positional params: e.g. `http_get(url, headers := PackedStringArray(), options := null)`, `http_post(url, body := "", headers := PackedStringArray(), options := null)`.
- Name the GET wrapper `http_get` (not `get`) to avoid colliding with the built-in `Object.get()`. For consistency, prefix the whole set: `http_head`, `http_post`, `http_put`, `http_delete`, `http_options`, `http_patch`.
- Additive and non-breaking; targeted at a post-1.0 release.

Start at the existing static request() and request_raw() entry points and trace their parameters and delegation behavior. Add one prefixed wrapper for each listed HTTP verb with the requested positional parameters, then verify each delegates through the existing paths so redirects, SSE, cancellation, and progress remain supported.

Written by the indexing model from the issue text.