Syntaxes: IntelliSense not available for inline styles

[stoneLeaf]

🚀 feature request

Description

Component inline styles have syntax highlighting but are missing IntelliSense auto completion:

Compared to styles in a standalone file:

Feature Type

What does this bug affect

• Angular Language Service VSCode extension
• Angular Language Service server

Describe the solution you'd like

The VSCode extension vscode-inline-html is able to do it using these syntaxes:
https://github.com/pushqrdx/vscode-inline-html/blob/f3cf6f071aa3ad86d0b3b3adc54fab42696a6b77/syntaxes/es6.inline.scss.json

I am not familiar enough with VSCode syntaxes files to spot what is missing in the current implementation:
https://github.com/angular/vscode-ng-language-service/blob/dab7f98334c8d11da0fe04c5c17202fad535a3a9/syntaxes/inline-styles.json

Describe alternatives you've considered

Using a third party extensions such as vscode-inline-html is cumbersome as it requires to tag the template literals in each component.

[pjpscriv]

Relevant Stack Overflow question where someone hit the same issue: https://stackoverflow.com/q/79683508