(Session Three) Fixes file.c nameLen member usage

[Menshin]

In the file.c exercice of the session three, info->nameLen seems to not work as intended :

• it's set while reading the keyfile (and not the username file) and always valued 3 (4 bytes read for an int, minus one).
• it's then used to allocated memory for the password calculation (which can only be of length greater or equal to 8), leading to write outside the allocated memory.

I've restored it to its percieved intended usage : set when reading the username file (discarding the linefeed char) and used to properly bound the password calculation/check.

Also fixes some minor typos in error messages while i was at it.
There's also some issues with malloc not being properly freed but i think that's mostly done to keep the code structure simpler to RE.

If this PR goes in, the binary will have to be regenerated too.
Please disregard if irrelevant, thanks for the good course anyway !

[wrongbaud]

Will merge and rebuild the binary, thank you for finding this! There are undoubtedly more things that slipped through when I developed this so I really appreciate you taking the time to help make this better!