Add find_framework() method to compiler object

[judemille]

Right now, it is impossible to add a framework dependency that is in a
non-standard path through Meson, without significant pain. This feature
allows the location of frameworks like normal libraries, with specification
of search paths.

[eli-schwartz]

What's the advantage of this new compiler method vs adding a new keyword argument to dependency() (specific to the appleframeworks method)?

[judemille]

What's the advantage of this new compiler method vs adding a new keyword argument to dependency() (specific to the appleframeworks method)?

I added it this way to be analogous to compiler.find_library(). Perhaps that wasn't the right move. I can look into adding keyword arguments to dependency().