tools: update eslint-plugin-markdown to 1.0.0

For eslint-plugin-markdown, we had been using an RC but can now use the
most recent stable release of 1.0.0, as it has the bugfix that caused us
to start using the RC in the first place.

There are a few other updates in this commit too because it was
performed by running `update-eslint.sh`. This did not update ESLint
itself but did update some dependencies.

PR-URL: #26345
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>