feat: use `eslint-plugin-userscripts`

[Yash-Singh1]

Adds the eslint-plugin-userscripts plugin to validate userscript metadata.

Here are the changes that could result in functionality differences summarized:

• I found some of the versions used the following format: vx.x.x Alpha, and changed them to vx.x.x-alpha. I am not sure if Tampermonkey supports this format, but there isn't any examples with such a format in their documentation: https://www.tampermonkey.net/documentation.php#meta:version . Also, ViolentMonkey doesn't support this version in their version comparison: https://github.com/violentmonkey/violentmonkey/blob/8627b2a3896a00a31e383c4ebf3eb21a25e757f2/src/common/util.js#L135
• I modified Userscripts.org_Extended_Style/37212.user.js to include 0.0.1 as the @version

The rest were autofixes for code style (e.g. spacing between metadata and code, attribute spacing, name at top, etc).

[Yash-Singh1]

The only remark I have is that most of my scripts are not relevant anymore or even deprecated. I don't want to alter those anymore (e.g. userscripts.org). Maybe we can exclude those from linting. When I find the time I'll update the readme with only the relevant userscripts, so we exclude all others here.

I updated the PR now to remove all edits on Userscripts.org and add it to the ESLint ignore path.