Use the new sass library instead of node-sass

[gagik]

Is your feature request related to a problem? Please describe.
CI seems to have updated to python 3.12 by default. node-sass is deprecated and was breaking CI lint because one of its dependencies was using a python standard library which was removed in 3.12: nodejs/node-gyp#2869. Right now the issue is "fixed" by setting our Python version to 3.11 but it'd be good to have latest sass installed which removes the need for this.

sass will also help us ensure better compatibility with the arm64 runner.

Describe the solution you'd like

1. Remove node-sass.
2. Remove the Setup Python 3.11 from the linting GitHub Actions workflow.
3. Add sass as a dependency.
4. Fix sass warnings we have in our repository (mainly related to deprecated SASS properties).

Describe alternatives you've considered
We can also just continue using node-sass and Python 3.11 or wait for a potential update of the library.

Additional context
See #1651

[sync-by-unito]

➤ PM Bot commented:

Jira ticket: RSTUDIO-538

[kraenhansen]

As discussed elsewhere, this is probably caused by sass/node-sass#3033 since the macos-latest runner on GHA is now arm64.