refactor: use shims instead of direct operations on PATH

[aooohan]

fix #253
fix #84
fix #235
fix version-fox/vfox-golang#9

Instead of modifying the PATH directly, this change uses the fixed path $VFOX_HOME/shims and $VFOX_SHELL_TMEP/shims instead.

Currently, the way to generate shim is very violent, later we need to ask plugins to tell vfox what bins need to be generated shim. see #191 (comment)

[aooohan]

[aooohan]

[aooohan]

There's a problem on Windows, so change this to a draft.

[jan-bar]

There's a problem on Windows, so change this to a draft.

As I expected the directory to be the link instead of the executable file, many tools' executable programs will depend on the directory they are in.

Just like https://github.com/Schniz/fnm

[aooohan]

As I expected the directory to be the link instead of the executable file, many tools' executable programs will depend on the directory they are in.

Yes. It's not that big of a problem, we can just implement the program exactly as mentioned in #84.

[jan-bar]

Yes. It's not that big of a problem, we can just implement the program exactly as mentioned in #84.

I like the soft link directory solution very much. I have used several version management tools using this method and it works well. I look forward to this implementation.

[aooohan]

The problem on Windows has been solved, and the original plan is still used.