CLI's checkForChanges method should not check all `node_modules`

[rosen-vladimirov]

Is your feature request related to a problem? Please describe.
CLI's watcher for node_modules should watch only the plugin's native files. With changes for 6.0.0 release, webpack will automatically watch all required files, even when they are from node_modules. When a change in some of the native files is applied, CLI's watcher will be triggered. In this case, the logic of CLI will be triggered to check if the node_modules are modified. It will list all files in node_modules just to determine if there's a change in any of them. Instead of listing all node_modules, CLI should check only the nativescript plugins and their platforms/<platform> directories.

Describe the solution you'd like
Change this code to list only <project dir>/node_modules/<nativescript plugin name>/platforms/<current platform> directories.

nativescript-cli/lib/services/project-changes-service.ts

Lines 77 to 81 in a4cb42c

	this._changesInfo.nativeChanged = projectChangesOptions.skipModulesNativeCheck ? false : this.containsNewerFiles(
	path.join(projectData.projectDir, NODE_MODULES_FOLDER_NAME),
	path.join(projectData.projectDir, NODE_MODULES_FOLDER_NAME, "tns-ios-inspector"),
	projectData,
	this.fileChangeRequiresBuild);

Describe alternatives you've considered
Refactor the whole checkForChanges logic, but this requires more time.

Additional context

[adrian-niculescu]

This is only desirable during the development of 1 plugin and would cripple other development flows.
The current behaviour should be kept (and be configurable maybe) to allow:

• debugging of any node_modules file://... dependency.
• debugging of a plugin that is used inside of another plugin (recently needed this with a a permissions management plugin used inside another one).