feat: Add prettier.config to clearUnnecessaryFiles.ts (#1051)

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## PR Checklist

- [X] Addresses an existing open issue: fixes #1019 
- [X] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [X] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Added `.prettier.config.js`, `.prettier.config.mjs` and
`.prettier.config.cjs` to `clearUnnecessaryFiles.ts` in order for those
files to be removed.

Author: jaas666

src/steps/clearUnnecessaryFiles.ts

@@ -4,6 +4,7 @@ const globPaths = [
 	...extensions(".babelrc", "cjs", "cts", "js", "json", "mjs"),
 	...extensions(".eslintrc", "js", "json", "yml"),
 	...extensions(".prettierrc", "json", "json5", "yaml", "yml"),
+	...extensions("prettier.config", "js", "mjs", "cjs"),
 	...extensions("babel.config", "cjs", "cts", "js", "json", "mjs"),
 	...extensions("jest.config", "cjs", "js", "json", "mjs", "ts"),
 	"./src/**/*.js",