style: Add pre-commit checks to fix whitespace

[bocan]

What does this PR change? What problem does it solve?

This changes no functionality, but cleans up a number of code styling issues. I've added a pre-commit configuration file, that optionally allows one to run pre-commit install after cloning, and from then on when you commit changes, it will run pre-commit against the code.

Specifically, it's setup to check for unnecessary trailing whitespaces, mixed windows/unix line endings, and missing end-of-file markers.

Was the change discussed in an issue or in the Discussions before?

Yes, in #1584.

PR Checklist

• [ ] This change adds/updates translations and I have used the template present here.
• [x] I have enabled maintainer edits for this PR.
• [x] I have verified that the code works as described/as intended.
• [ ] This change adds a Social Icon which has a permissive license to use it.
• [x] This change does not include any CDN resources/links.
• [x] This change does not include any unrelated scripts such as bash and python scripts.
• [ ] This change updates the overridden internal templates from HUGO's repository.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud