feat(debugging): move gdbinit generation to CMake

This feature is useful for 3rd-party software to run GDB with predefined
options that described in project_description.json file

allow to pass custom options to "idf.py gdb":

  --gdb-commands: command line arguments for gdb. (without changes)
  -ex: pass command to gdb.
  -x: pass gdbinit file to gdb. Alias for old --gdbinit command

tools/cmake/symbols.gdbinit.in

@@ -0,0 +1,9 @@
+${rom_symbols}
+
+# Load bootloader symbols
+set confirm off
+  ${add_bootloader_symbols}
+set confirm on
+
+# Load application symbols
+file ${application_elf}