Write config parser

[wizard-28]

The config file should be in the toml format, and should be stored in /etc/pacstall/config.toml (allow this location to be customized).

Progress:

• feat: add initial config parser module #13

[wizard-28]

We should use tomli as this is the fastest pure python parser.

Article comparing toml parsers.

Benchmark:

------------------------------------------------------
    parser |  exec time | performance (more is better)
-----------+------------+-----------------------------
     rtoml |    0.891 s | baseline (100%)
  pytomlpp |    0.969 s | 91.90%
     tomli |        4 s | 22.25%
      toml |     9.01 s | 9.88%
     qtoml |     11.1 s | 8.05%
   tomlkit |       63 s | 1.41%