fix: merge fetchOptions from HttpRpcClient options with request-specific options

[mlshv]

While integrating proxies in viem as per the recent fix, I noticed that the implementation was only considering request-specific fetchOptions and skipping those passed to the HTTP transport

This PR fixes it by merging the fetchOptions from the HttpRpcClient options with those from individual requests

For anyone facing this issue, you can use a temporary fix until the PR is merged:

1. Install patch-package
2. Add npm script "postinstall": "patch-package"
3. Open node_modues/viem and go to folder that corresponds to module systems currently being used (_esm, _cjs)
4. Edit getHttpRpcClient function from utils/rpc/http.js: add ...(options.fetchOptions || {}), at the first line of const init = { object.
5. Run npx patch-package viem

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PR-Codex overview

This PR fixes the declaration of fetchOptions on HTTP RPC.

Detailed summary

• Fixed fetchOptions declaration on HTTP RPC in http.ts
• Updated fetchOptions object merging logic to include both options and params properties.

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🦋 Changeset detected

Latest commit: 3bd83cc

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
viem	Patch

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