Update linter style to use 4-space indents

This commit adds a custom .clang-format config file to switch the LLVM C++ style guide's default 2-space indents to 4-space indents. The config file is read
by clang-format in the action after updating linter.yml to use `clang_format_args: -style=file`.

Author: Hiemstra

.clang-format

@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+IndentWidth: 4

.github/workflows/linter.yml

@@ -41,6 +41,6 @@ jobs:
           commit: true 
           continue_on_error: false
           git_email: github.event.commits[0].author.name # Uses the author's git email instead of the default git email associated with the action ("lint-action@samuelmeuli.com")
-          #clang_format_args: # Any additional arguments for clang_format
+          clang_format_args: -style=file # Any additional arguments for clang_format