Add support to set proxy in http and grpc directives

[tusharmath]

Currently http and grpc doesn't support proxy and can only be configured via upstream. We need to change that:

Technical Requirements

• It proxy setting is configured both at upstream and at http and grpc we should prefer the one that's local over the global setting.
• Add unit tests to ensure the http/grpc client use the provided proxies for making HTTP calls.

[tusharmath]

/bounty $190

[algora-pbc]

💎 $190 bounty • Tailcall Inc.

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Attempt	Started (GMT+0)	Solution
🟢 @beelchester	Sep 16, 2024, 1:46:07 AM	#2826

[beelchester]

/attempt #2820

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