cmake: modules: Add zephyr_library_add_dependencies extension

Add a CMake zephyr library extension for add_dependencies, similar
to the target_<func> functions.
This avoids using ${ZEPHYR_CURRENT_LIBRARY} directly.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>
diff --git a/cmake/modules/extensions.cmake b/cmake/modules/extensions.cmake
index 061ed77..6bdd554 100644
--- a/cmake/modules/extensions.cmake
+++ b/cmake/modules/extensions.cmake
@@ -528,6 +528,10 @@
   endforeach()
 endfunction()
 
+function(zephyr_library_add_dependencies)
+  add_dependencies(${ZEPHYR_CURRENT_LIBRARY} ${ARGN})
+endfunction()
+
 # Add the existing CMake library 'library' to the global list of
 # Zephyr CMake libraries. This is done automatically by the
 # constructor but must be called explicitly on CMake libraries that do
@@ -1819,6 +1823,12 @@
   endif()
 endfunction()
 
+function(zephyr_library_add_dependencies_ifdef feature_toggle)
+  if(${${feature_toggle}})
+    zephyr_library_add_dependencies(${ARGN})
+  endif()
+endfunction()
+
 macro(list_append_ifdef feature_toggle list)
   if(${${feature_toggle}})
     list(APPEND ${list} ${ARGN})
@@ -1965,6 +1975,12 @@
   endif()
 endfunction()
 
+function(zephyr_library_add_dependencies_ifndef feature_toggle)
+  if(NOT ${feature_toggle})
+    zephyr_library_add_dependencies(${ARGN})
+  endif()
+endfunction()
+
 macro(list_append_ifndef feature_toggle list)
   if(NOT ${feature_toggle})
     list(APPEND ${list} ${ARGN})