Feature description

Allow users to add their own keys to message-colors f.e.:

message-colors:
`

primary: '#ffaa00'
secondary: '#ff5555'
infoWithPrefix: '<dark_gray>[<#ffae3a>MyServerPrefix<dark_gray>] <gray>'

`
make infoWithPrefix work in messages like or something

How the feature is useful

That would make messages file more simple and less confusing for server owners