[FEATURE] ls command doesn't show files date / timestamp

### Is your feature request related to a problem? Please describe.

NuttX "ls -l" command currently doesn't show the file timestamp, although this information is stored in some filesystems supported by NuttX.

### Describe the solution you'd like

Modify ls_handler() to print timestamp when it is available.

### Describe alternatives you've considered

_No response_

### Verification

- [x] I have verified before submitting the report.