fix(amazonq): add flag in settings for controlling experimental proxy support

[tsmithsz]

Problem

The proxy and certificate auto-discovery code occasionally causes issues and there is a need to allow control of this by users.

Solution

Add a checkbox in settings that allow customers to control whether they want Amazon Q's proxy and certificate auto-discovery turned on.

Testing

Experimental proxy util used once setting enabled:

Standard proxy util used once setting disabled:

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[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
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[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.