Add renamel command and unittests to rename local files from current working directory

[svuhoang]

Implemented the 'renamel' command to perform renaming of local files from current working directory, which may or may not include paths Added the unit testing for the rename command.

Acceptance Criteria:

• [x] Verify that a given file exists locally, and a new file name is given for the existing file to be renamed to
• [x] Verify that nested files can also be renamed from a local path