add .clang-format for formatting cpp code

.clang-format

+---
+BasedOnStyle: LLVM
+ColumnLimit: 120
+IndentWidth: 4
+TabWidth: 4
+UseTab: ForIndentation
+AlignEscapedNewlines: DontAlign
+AllowShortFunctionsOnASingleLine: Inline
+AlwaysBreakTemplateDeclarations: Yes
+BreakBeforeBinaryOperators: NonAssignment
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterFunction: true
+...

.vscode/tasks.json

+{
+    "version": "0.1.0",
+    "tasks": [
+        {
+            "taskName": "clang-format-everything",
+            "command": "clang-format",
+            "args": ["-i", "*" ],
+            "isShellCommand": true,
+            "isBackground": true
+        }
+    ]
+}
\ No newline at end of file