Support angular.json configuration for tsconfig

[SpencerKaiser]

🚀 feature request

Description

angular.json supports the configuration of specifying a tsconfig to use instead of just pulling from tsconfig.json at the root. In the scenario where you have multiple tsconfigs, it's likely you may want to separate things like angularConfiguration out of the root tsconfig.json - in this scenario, it'd be ideal for the VS Code extension to pull the relevant tsconfig from angular.json instead of defaulting to /tsconfig.json.

Feature Type

What does this feature affect

• Angular Language Service VSCode extension
• Angular Language Service server

Describe the solution you'd like

Support for the angular.json configuration option for tsConfig:
projects.app-root.architect.build.options.tsConfig

Describe alternatives you've considered

Adding to my main tsconfig.json 😢

Anything else relevant?

This is a duplicate of #1667 but that issue was closed due to inactivity