MISC: Add sample configuration files

.clangd

+If:                               # Apply this config conditionally
+  PathMatch: .*\.h                # to all headers...
+  CompileFlags:                     # Tweak the parse settings
+    Add: [-xc++, -Wall]             # treat all files as C++, enable more warnings

.gitignore

+# CMake stuff
+Violet
+Violet_autogen/*
+Vivy
+Vivy_autogen/*
+compile_commands.json
 CMakeCache.txt
 CMakeFiles/*
 Makefile
-Violet
-Violet_autogen/*
 cmake_install.cmake
 .cache/*
 Debug/*
-compile_commands.json
+
+# Build folder
 build/*
+
+# Local configurations
+.vim/*

utils/samples/dot-ccls

+-isystem
+/usr/local/include
+-isystem
+/usr/include/x86_64-linux-gnu
+-isystem
+/usr/include/x86_64-linux-gnu/qt5/QtCore
+-isystem
+/usr/include/x86_64-linux-gnu/qt5/QtWidgets
+-isystem
+/usr/include
+-I
+./inc
+./build/Vivy_autogen/include
+-std=c++20
+-fPIC
+-D__linux__

utils/samples/dot-vim-slash-coc-settings.json

+{
+    "languageserver": {
+        "clangd": {
+            "command": "clangd",
+            "rootPatterns": ["compile_commands.json"],
+            "filetypes": ["c", "cpp", "objc", "objcpp"]
+        }
+    },
+    "clangd.semanticHighlighting": true
+}