Implement FCOPY

FCOPY needs to be implemented that implements the [C]opy function that is in CONFIG, as a tool that can be used outside of CONFIG.

You can use any of the F* or N* tools as a template to get any code you need.

How it needs to work:

```
FCOPY ,,,
```

example:

```
D1:FCOPY 2,/some/path/to/file,1,/some/path/to/destination/file
```

The copy command is described here:
https://github.com/FujiNetWIFI/fujinet-platformio/wiki/SIO-Command-%24D8-Copy-File

and the code that config uses, is here:
https://github.com/FujiNetWIFI/fujinet-config/blob/master/src/diskulator_copy.c

Start by examining the existing F* and N* tools in this repository as templates, then compare CONFIG's implementation in diskulator_copy.c with the SIO Command $D8 Copy File documentation. Implement the FCOPY command using the stated four-argument syntax and verify that it copies between the specified host slots and paths.

Written by the indexing model from the issue text.