chore: split into file per function

* split write.ts into one file per function

.editorconfig

@@ -0,0 +1,5 @@
+root = true
+
+[*.ts]
+indent_style = space
+indent_size = 4

src/index.ts

@@ -1,6 +1,7 @@
 import * as core from '@actions/core';
 import { configFromJobInput } from './config';
 import { extractResult } from './extract';
+
 import { writeBenchmark } from './write';
 
 async function main() {