feature: autocomplete for media queries

[jesperjen98]

Implementation of media query autocomplete for both media types and
features. The implementation is based on how the IProperyData interface
is implemented and may therefor contain a small amount of redundant
code. The modified files are: cssLanguageTypes.ts, webCustomData.ts,
dataManager.ts, dataprovider.ts, entry.ts, cssCompletion.ts.

[ghost]

All CLA requirements met.

[aeschli]

Cool thanks! You are extending the css custom data format and we should also update the related resources:

• the schema at https://github.com/microsoft/vscode-css-languageservice/blob/main/docs/customData.schema.json
• the documentation at https://github.com/microsoft/vscode-css-languageservice/blob/main/docs/customData.md
• (ideally) have the generator for the default profile include the built-in queries: https://github.com/microsoft/vscode-custom-data/blob/main/web-data/css/generateData.js

[jesperjen98]

Sorry for a late response once again, I have a lot of work right now finishing upp my courses but I will try to do this before the end of the new year. Thank you very much for the feedback!

[soredake]

@jesperjen98 any progress on this?