cmake: binaryninjaui depends on binaryninjaapi

[ekilmer]

Fixes building the uinotification example that only links against binaryninjaui.

Without this fix, there's a compilation error about not finding binaryninjaapi.h:

In file included from binaryninja-api/examples/uinotification/uinotification.cpp:2:
In file included from binaryninja-api/examples/uinotification/uinotification.h:3:
binaryninja-api/ui/uicontext.h:8:10: fatal error: 'binaryninjaapi.h' file not found
    8 | #include "binaryninjaapi.h"
      |          ^~~~~~~~~~~~~~~~~~
1 error generated.

[ekilmer]

The uinotification build error can be repeated when running the following commands on dev branch (assuming CMake can find the binaryninjaui shared library):

cmake -B build -S . -G Ninja -DHEADLESS:BOOL=OFF -DBN_API_BUILD_EXAMPLES:BOOL=ON
cmake --build build --target uinotification