Applying the feedback given by @pluiedev to use an enum to specify the
type of quick terminal size configuration given (pixels or percentage).
Updated the Swift code to work with the enum as well.
Added C bindings for the already existing quick-terminal-size
configuration. Created a new QuickTerminalSize struct to hold these
values in Swift. Updated the QuickTerminal implementation to use the
user's configuration if supplied. Retains defaults. Also adds support to
customize the width of the quick terminal (height if quick terminal is
set to right or left).
