mcumgr: Add a copy of image management lib

Add a copy of the img_mgmt.c file, so it can be adjusted to work
with all NCS-specific extensions.

Zephyr revision: 25269118b5069ebb72316d2a26bdedbe6ba8de95

Signed-off-by: Tomasz Chyrowicz <[email protected]>

Author: tomchy

subsys/mgmt/mcumgr/grp/img_mgmt/CMakeLists.txt

@@ -7,9 +7,16 @@
 if(CONFIG_MCUMGR_GRP_IMG_NRF)
   zephyr_library_amend()
   zephyr_library_sources(
+    src/img_mgmt.c
     src/img_mgmt_state.c
   )
 
+  set_source_files_properties(
+    ${ZEPHYR_BASE}/subsys/mgmt/mcumgr/grp/img_mgmt/src/img_mgmt.c
+    DIRECTORY ${ZEPHYR_BASE}/subsys/mgmt/mcumgr/grp/img_mgmt/
+    PROPERTIES HEADER_FILE_ONLY ON
+  )
+
   set_source_files_properties(
     ${ZEPHYR_BASE}/subsys/mgmt/mcumgr/grp/img_mgmt/src/img_mgmt_state.c
     DIRECTORY ${ZEPHYR_BASE}/subsys/mgmt/mcumgr/grp/img_mgmt/