Refactor browser source (Browser Source ver. 2.0)

This significantly reduces the complexity and increases the readability
of the browser source's codebase.  This prunes approximately 13,000
lines of unnecessary code, and reduces the core browser source files
from ~65 files to ~10.

1.) Removes macOS CEF process isolation (an alternative means of load
    isolation was added to the frontend)
2.) Removes unnecessary dependencies such as fmt and nowide
3.) Switches from jansson to json11 to make it a bit easier to compile
    on windows (jansson is compiled with DLL redistributables, where as
    the browser source plugin is compiled without)
4.) Removes unnecessary ::Impl classes (should have been abstract
    classes with virtual functions from the beginning, the only reason
    to use private implementation classes like this are when you want to
    hide implementation, not when you want to simply abstract
    implementation)
5.) Combines files that were unnecessarily spread apart
6.) Unifies the design across operating systems
7.) Improves the readability of the code
8.) Removes all memory leaks
9.) Opens up the ability to implement Linux support more more easily
    later

(Author note: I did not want to have to make commits for every single
change at this point.  I realize that this would have been ideal to
track specific changes, but it's nearly on the level of being a rewrite.
The browser source codebase was in such disrepair that I just decided it
was not worth my time at this point.  Consider this commit executive
privilege for this one particular case.)