maint: tweak .gitignore and remove redundant files

combine code/.gitignore and the one at the root of the repo

.bandit was part of codacy checks suite, current python code
should probably be updated to use either pylint directly and (/ or)
through the codeql python workflow

.bandit

@@ -1,3 +0,0 @@
-# Ignore B404 "Avoid importing subprocess"
-# Ignore B603 "Subprocess without shell equals true"
-skips: ['B404', 'B603']

.gitignore

@@ -1,19 +1,25 @@
-*.s#?
 *.b#?
-.modgit
-firmware*
 *.gch
-.pio*
+*.py[cod]
+*.s#?
+.DS_Store
 .clang_complete
+.env
 .gcc-flags.json
-.sconsign.dblite
-credentials.h
-node_modules
-code/utils
-custom.h
+.modgit
+.pio
 .python
-.env
-.DS_Store
+.python-version
+.sconsign.dblite
 .vscode
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
 _pycache_/
-*.py[cod]
+code/.cache/
+code/espurna/config/custom.h
+code/libraries/
+code/node_modules
+code/test/unit/cache
+compile_commands.json
+firmware*

code/.gitignore

@@ -1,15 +0,0 @@
-.clang_complete
-core_version.h
-custom.h
-.DS_Store
-.gcc-flags.json
-.python-version
-.travis.yml
-.vscode
-.vscode/.browse.c_cpp.db*
-.vscode/c_cpp_properties.json
-.vscode/launch.json
-.pio
-test/unit/cache
-libraries/
-espurna/espurna.ino.cpp