can't propogate header across grpc protocol in wasm plugin

[JhouXerox]

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Ⅰ. Issue Description

can't add/replace header across grpc protocol in wasm plugin.

grpc代理的流量无法新增/覆盖header,无法传播新增的头

Ⅱ. Describe what happened

I need to replace or add some header in wasm plugin, currently I use golang to build wasm plugin,in plugin I try to add some header like 'x-custom-user-id' , 'x-custom-permission' ...
but in my grpc service side, when request come in, I can't see any new header added in wasm on my request metadata

我需要再wasm插件中覆盖或新增一些头,当前我使用golang语言来构建wasm插件,在插件中我尝试添加一些自定义的头,例如'x-custom-user-id', 'x-custom-permission'. 这些头我增加来是为了后续的金丝雀能力
但是在我的grpc服务端侧,当请求进来的时候,我在metadata中看不到我在插件中新增的头.

Ⅲ. Describe what you expected to happen

headers added or replaced in my wasm plugin should as metadata to grpc request, and recognize by canary policy.
插件中新增的头应该能够作为metadata继续传播下去,并且可以被金丝雀策略识别

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. make sure there's an grpc route 确保有一个grpc的路由策略
2. make a golang wasm plugin, and try add a head in onRequestHeader 搞一个go的wasm插件,在插件里onRequestHeader添加一个头
3. see if there has the new head in matadata on grpc server side. 看grpc服务端有没有插件中新加的头

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• Higress version: 1.3.5
• OS : k8s
• Others: