Tools - none-cxxflags generator script & enable deprecation warnings (#9245)

* Tools - none-cxxflags generator script

GCC10 -> GCC (as in general, not specific to 10)
cpp -> cxx to be consistent with gcc terminology
grep exclude patterns in a separate file
exclude 'deprecated' warnings by default

* actually set warnings when compiling

--warnings=none is arduino-cli implicit default

tools/warnings/make_none-cxxflags.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env sh
+
+root=$(git rev-parse --show-toplevel)
+${CC:-xtensa-lx106-elf-gcc} --help=warnings -Q |\
+    grep '\[enabled\]' |\
+    grep -v 'return-type' |\
+    awk '{print $1}' |\
+    sed 's/-W/-Wno-/' |\
+    grep -v = |\
+    grep -v -f ${root}/tools/warnings/patterns_none-cxxflags.txt |\
+    sort -u > ${root}/tools/warnings/none-cxxflags