Terminal and Font Transparency Controls

[excalith]

Discussed in #57

^{Originally posted by g4xx January 5, 2024}
It would be nice to separate terminal transparency from font transparency. Currently using opacity parameter really hurts legibility of text if set too low. This of course could be two separate parameters in config.

Currently, the terminal opacity changes the whole opacity of the terminal, including text. It can be further improved by adjusting terminal background and text opacity individually, giving more freedom for customization.