Support optional custom working directory

[agarzola]

Description

Some projects require package manifests and lockfiles in a nested directory (i.e. not the root of the project). For such cases, this action should provide a solution that allows users to indicate which directory within the project should be checked for a lockfile.

Proposed Solution

Add a working-directory argument to the action. This argument should be passed to the script, which should in turn use it to navigate to the appropriate directory (if one is declared).

Alternatives Considered

n/a

Additional Context

n/a