This adds a short lint to ensure that all files have a single trailing newline and no trailing whitespaces. This PR is in two commits, one to add the check and another to fix currently offending files in the repo. See https://github.com/apache/tvm/pull/13058/commits/ba2c2e235e2a16d62fdeed959044c65012d9f942 for just the significant changes. Auto-corrections applied with

```
pre-commit run --all-files
```