Resolve transitive dependencies based on package.json

[seanoch]

When the newly added resolveDependenciesFromPackageJson flag is set to true, ATA will resolve the versions of any transitive dependency according to the package.json file of the same module (unless any // types: comment is specified).

[seanoch]

@microsoft-github-policy-service agree company="wix"

[tomenden]

See small comments regarding naming.
I suggest adding a bit more context in the PR description to explain the motivation. I think an example will help the typescript team understand what you did here

[tomenden]

Suggested change

	let typesPackageJson
	if (config.usePackageJson){
	typesPackageJson = moduleMap.get(dts.moduleName)?.typesPackageJson
	}
	const typesPackageJson = config.usePackageJson && moduleMap.get(dts.moduleName)?.typesPackageJson

[jakebailey]

To be clear, is the intent here to ensure that all dependencies are loaded transitively?

Should this flag be set for the website? Should it be disabled at all?

[seanoch]

@jakebailey The intent is to allow resolution of transitive (indirect) dependencies according to their module's package.json file. Before this change, any indirect dependency gets resolved to latest, since the only way to control versioning is via the // types: comment, which is controllable only in the first input file.

For example, if the input file says import a from 'PackageA', and some of PackageA's types imports from PackageB -

• Before this change, any d.ts from PackageB will be resolved to PackageB@latest
• After this change, any d.ts from PackageB will be resolved to the version of PackageB that is specified in PackageA's package.json.

[seanoch]

@jakebailey Hi, is any additional explanation needed before a review?