Add overwrite input to optionally allow copying over existing dependency files from non-root directories

[aparnajyothi-y]

Description:
Adds an overwrite input to prevent unintended overwrites when a composite action defines a cache-dependency-path (e.g., subdir/requirements.txt) that matches a file in the user’s workspace. By default, the copy is skipped if the target file exists, unless overwrite: true is explicitly set. This avoids silently replacing user files with the same name and path structure.

Check list:

• [ X] Mark if documentation changes are required.
• [ X] Mark if tests were added or updated to cover the changes.