Speed up get_packages

[SleepyBag]

Description

Speed up the performance of get_packages by redesign the flow.

Currently, get_package runs unacceptably slow on WSL. The reason is its call to type. Each fail type call can consume 0.1s on a WSL machine. There are too many package managers to check and in total the checks consume too much time.

So, in the new flow, all the package managers are checked at once by list all executables in $PATH directories and then grep all the files. Thus we get a hit file list of possible package managers. Then each has call can just run type for package managers who show in the hit list.

On WSL, the upgraded version is much faster than the original one.

Before modification:

real    0m2.513s
user    0m0.043s
sys     0m0.464s

After modification:

real    0m0.414s
user    0m0.151s
sys     0m0.053s

TODO

This branch is only tested on a WSL machine. The influence on other platforms is unknown yet.

[hykilpikonna]

Optimization is great! But neofetch isn't something that people run a lot, so I think compatibility is more important than performance here