fix(config): expand home in GitHub token file read and use token for rate

[hhromic]

This PR fixes three issues I found while testing the new GitHub token reading from files:

• The ~/ home directory shortcut was not expanded, for example in @~/secrets/github-token.
• When loading a GitHub token from file, the newline/carriage-return at the end of the file were also read into the token.
• When using the --rate option, the GitHub token stored in a config file was not used.

For the second point I used strings.TrimRight(), which strips any of the \r\n runes. Therefore, the trimming works properly for all OS line-ending styles (Unix, Mac, Windows).

To fix the third point, I had to separate the loading of global options from project options into two different functions so the global options can be loaded earlier for the --rate option to have a populated GitHub token from a config file.