Add support for replace directive in go.mod files

[uttam282005]

Fixes #3492

1. Parsing Replace Directives (go_mod.py)

• Added handle_replace_directive() function to parse and categorize replacements:
• Parses both inline and block-style replace statements
• Distinguishes between local path and remote replacements
• Stores original module in exclude list (as it's being replaced)
• Stores replacement in require list (remote) or local_replacements (local)

2. Local Replacement Resolution (golang.py)

• Added resolve_local_replacements() method that:
• Traverses the codebase to locate local replacement targets
• Resolves relative paths (e.g., ../pkg/) to absolute paths
• Extracts package metadata from target's go.mod file
• Creates resolved dependency entries with full package information

3. Assembly Integration

Modified BaseGoModuleHandler.assemble() to:

• Resolve local replacements after package assembly
• Ensure resolved dependencies are included in final output

This PR is inspired by the work done by @shravankshenoy and maintainer reviews on PR #3693.

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

[Copilot]

Pull request overview

This PR adds support for parsing replace directives in Go module files (go.mod), enabling ScanCode to properly handle both local path and remote package replacements commonly used in Go projects.

Changes:

• Added parsing logic for replace directives in both inline and block-style formats
• Implemented resolution of local replacement paths to extract package metadata from target go.mod files
• Enhanced package data model to track local replacements and their resolved dependencies

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
src/packagedcode/go_mod.py	Added replace directive parsing functions, regex patterns, and local_replacements tracking in GoModule class
src/packagedcode/golang.py	Added resolve_local_replacements method to resolve local paths and integrate resolved dependencies into package data
tests/packagedcode/test_golang.py	Added two new test cases for milvus and gopls projects with replace directives
tests/packagedcode/data/golang/gomod/milvus/go.mod	New test fixture with mixed local and remote replace directives
tests/packagedcode/data/golang/gomod/milvus/output.expected.json	Expected parsing output for milvus test
tests/packagedcode/data/golang/gomod/gopls/go.mod	New test fixture with local replace directive
tests/packagedcode/data/golang/gomod/gopls/output.expected.json	Expected parsing output for gopls test
tests/packagedcode/data/golang/gomod/opencensus-service/output.expected.json	Updated expected output to include replace directive results

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