feat: grpc header forwarding

[potterbm-cb]

Motivation

Some blockchain networks (looking at you, cosmos) use grpc to communicate with the blockchain node.

This PR makes updates to the headerforwarder package to make it easy to use with grpc clients

Additional Improvements: Outgoing header forwarding

This PR also introduces functionality to set outgoing headers on both grpc and http requests. Previously this was accomplished by individual clients (actually only mesh-geth-sdk was modified so far) defining context-creation behavior. Unfortunately, the request context plumbing was pretty ungainly and required each caller of this SDK to implement their own code for it.

Now the outgoing headers will be captured in the server middleware, stored by request ID, and set on outgoing http and grpc requests via the http.RoundTripper and grpc.UnaryClientInterceptor respectively

Upgrade go version to 1.19

In order to get a version of grpc with a metadata bugfix this PR upgrades the go version of this module

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Notes to reviewers

All of the substantive changes here happen in the headerforwarder/ package.

Other changes fall into two categories:

• revert contextFromRequest changes from v0.8.6
  • these changes are concentrated in the templates/, client/, and server/ directories
• upgrade golang to 1.19
  • this is necessary because grpc uses the atomic package which isn't available in 1.18
  • this upgrade required removing all references to ioutil as it was deprecated and thus failing linting

[cb-heimdall]

✅ Heimdall Review Status

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