Save sketch recreate the sketch file and break the hard link

OS: macOS 10.14.6
IDE: 1.8.10
We create a hard link to a sketch:
```console
$ ln ~/Documents/Arduino/test/test.ino ~
$ ls -li ~/Documents/Arduino/test/test.ino ~/test.ino
12898678091 -rw-r--r-- 2 45gfg9 staff 225 2 14 13:21 /Users/45gfg9/Documents/Arduino/test/test.ino
12898678091 -rw-r--r-- 2 45gfg9 staff 225 2 14 13:21 /Users/45gfg9/test.ino
```
Go to IDE and change the sketch, then

```console
$ ls -li ~/Documents/Arduino/test/test.ino ~/test.ino
12898678261 -rw-r--r-- 1 45gfg9 staff 221 2 14 13:23 /Users/45gfg9/Documents/Arduino/test/test.ino
12898678091 -rw-r--r-- 1 45gfg9 staff 225 2 14 13:21 /Users/45gfg9/test.ino
```

Reproduce the save operation on macOS 10.14.6 with Arduino IDE 1.8.10 using the hard-link commands from the report. Trace the sketch-file save path and verify that saving preserves the original inode and hard link; confirm this with the reported ls -li comparison.

Written by the indexing model from the issue text.