Fix requirement which override

[MikeMcQuaid]

Fixes #22036

• preserve Requirement#which defaulting to ORIGINAL_PATHS
• match Kernel#which arity and visibility for Sorbet
• cover which inside satisfy(build_env: false) regression

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[Copilot]

Pull request overview

Fixes Requirement#which so it properly overrides Homebrew’s Kernel#which (matching arity/visibility for Sorbet), while still defaulting to ORIGINAL_PATHS. Adds a regression spec to ensure which calls from satisfy(build_env: false) don’t error.

Changes:

• Update Requirement#which to accept the same parameters as Kernel#which, use override, and make it public.
• Preserve Requirement#which default path behavior (defaulting to ORIGINAL_PATHS).
• Add a spec covering which usage inside satisfy(build_env: false).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
Library/Homebrew/requirement.rb	Aligns Requirement#which signature/visibility with Kernel#which while preserving the ORIGINAL_PATHS default.
Library/Homebrew/test/requirement_spec.rb	Adds regression coverage for calling which inside satisfy(build_env: false).

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