fix: platform remove command fails with old Android runtime

After upgrading `nativescript-doctor`, the version of the Java is
validated against the current Android runtime version. In case the
runtime version cannot work with Java 10, `nativescript-doctor` does not
allow the operation to continue. This breaks the `platform remove`
command, as it checks the system requirements first, before executing
the actual removal. However, this is no longer required as the code for
removing the platform is `try-catched` and in case the current
environment is not setup correctly, it will try to remove the
platforms/<platform> dir and the respective key in package.json.
So remove the environment validation from this command. Also remove the
`validatePlatformInstalled` call from the `canExecute` method of the
command, as it is actually called in the `removePlatforms` method.

Author: rosen-vladimirov

lib/commands/remove-platform.ts

@@ -3,8 +3,7 @@ export class RemovePlatformCommand implements ICommand {
 
 	constructor(private $platformService: IPlatformService,
 		private $projectData: IProjectData,
-		private $errors: IErrors,
-		private $platformsData: IPlatformsData) {
+		private $errors: IErrors) {
 		this.$projectData.initializeProjectData();
 	}
 
@@ -17,12 +16,9 @@ export class RemovePlatformCommand implements ICommand {
 			this.$errors.fail("No platform specified. Please specify a platform to remove");
 		}
 
-		for (const platform of args) {
-			this.$platformService.validatePlatformInstalled(platform, this.$projectData);
-			const platformData = this.$platformsData.getPlatformData(platform, this.$projectData);
-			const platformProjectService = platformData.platformProjectService;
-			await platformProjectService.validate(this.$projectData);
-		}
+		_.each(args, platform => {
+			this.$platformService.validatePlatform(platform, this.$projectData);
+		});
 
 		return true;
 	}