[BUG] Fix install script alias

[MrDevel0per]

Describe the bug
macOS automatically adds binaries in /usr/bin to PATH. Our install.sh script moves our built ally binary to that location - thus, the first line of the ally file ends up being:

alias ally="ally"

We should either fix this alias (i.e. not add it) or add an option to not add it or install in a different location.

Output

alias ally="ally"

THIS IS EXPECTED BEHAVIOR. This is also desired, as if the user installs in a location not on PATH, then we want this alias. We could fix it:

FIX
One, allow the user to specify --no-alias and also --overwrite (the second one is unrelated to this issue, but still good-to-have) when installing. Specify this --no-alias when calling ally init (which we might want to change to ally setup) from the script.