Split into multiple crates

[K4rakara]

As it is currently, freshfetch takes 10 or more seconds to compile on my 12-core AMD Ryzen 5 2600 running at 3.4GHz. Thats a bit much, even for Rust. How can this be fixed? By splitting the code into multiple crates, you can reduce compilation time.

I was thinking 3 crates:

• Core
• ASCII Art
• Info (the stuff that fetches system info)

Once its split into 3 crates, all we need to do is set up a Rust workspace.

Note: I'm not planning on implementing this for v0.1.3, rather for v0.2.0.