Default base_url for HTTP Client

[csgulati09]

Title: Default base_url for HTTP Client

Description:

• Adds default base_url to passed http client if not passed by the user

Motivation:
Sid asked for it

Related Issues:
Fixes: #402

[Copilot]

Pull Request Overview

This PR adds default base URL handling for custom HTTP clients passed to Portkey's sync and async client constructors. When users provide their own HTTP client without a base URL, the client will now inherit the base URL from the Portkey client configuration.

Key Changes:

• Added base URL defaulting logic for custom HTTP clients in both sync and async client constructors
• Ensures custom HTTP clients use Portkey's base URL when no base URL is explicitly set

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[Copilot]

The comparison http_client.base_url != \"\" may not correctly handle all cases where base_url is unset. HTTPX's base_url is a URL object, not a string, and when unset it defaults to an empty URL object (which doesn't equal an empty string). Consider using if not http_client.base_url or str(http_client.base_url) == \"\" for a more robust check.

Suggested change

	http_client.base_url if http_client.base_url != "" else self.base_url
	http_client.base_url if http_client.base_url and str(http_client.base_url) != "" else self.base_url

[Copilot]

The comparison http_client.base_url != \"\" may not correctly handle all cases where base_url is unset. HTTPX's base_url is a URL object, not a string, and when unset it defaults to an empty URL object (which doesn't equal an empty string). Consider using if not http_client.base_url or str(http_client.base_url) == \"\" for a more robust check.

Suggested change

	http_client.base_url if http_client.base_url != "" else self.base_url
	http_client.base_url if (http_client.base_url and str(http_client.base_url) != "") else self.base_url