Add Clone function to return shallow copy of slice collections

[quexer]

This PR adds a new Clone function to the slice utilities that returns a shallow copy of any slice collection.

Implementation

The Clone function uses the efficient append(collection[:0:0], collection...) pattern to create a shallow copy:

// Clone returns a shallow copy of the collection.
func Clone[T any](collection []T) []T {
	return append(collection[:0:0], collection...)
}

Usage

original := []int{1, 2, 3, 4, 5}
cloned := lo.Clone(original)

// Modifying the clone doesn't affect the original
cloned[0] = 99
fmt.Println(original) // [1 2 3 4 5]
fmt.Println(cloned)   // [99 2 3 4 5]

Features

• Type-safe: Works with any slice type using Go generics
• Efficient: Uses the slice reslicing pattern for optimal performance
• Nil-safe: Properly handles nil slices by returning nil
• Independence: Creates truly independent copies that don't share underlying arrays

Testing

Added comprehensive tests covering:

• Various slice types (int, string)
• Empty slices
• Nil slices
• Verification that modifications to cloned slices don't affect originals
• Example tests demonstrating usage

All existing tests continue to pass, ensuring no regressions.

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.47%. Comparing base (bededfe) to head (18cbc3c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #656   +/-   ##
=======================================
  Coverage   94.46%   94.47%           
=======================================
  Files          18       18           
  Lines        3290     3292    +2     
=======================================
+ Hits         3108     3110    +2     
  Misses        170      170           
  Partials       12       12           

Flag	Coverage Δ
unittests	94.47% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.