Read flipper-plugin from peer deps

Summary:
To know whether plugins should be mounted with the old setup or new setup (with a Provided / context based api), we need to be able to recognize whether a plugin is written with the old or new setup.

We do this by checking if the flipper-plugin dependency is declared as peer dependency. This we can to check for SDK compatibility as well.

Reviewed By: jknoxville

Differential Revision: D22043085

fbshipit-source-id: 21afabb6e58d86253a464470f4690c51cced87ab

desktop/plugin-lib/src/getPluginDetails.ts

@@ -58,6 +58,7 @@ async function getPluginDetailsV1(
     description: packageJson.description,
     category: packageJson.category,
     bugs: packageJson.bugs,
+    flipperSDKVersion: packageJson?.peerDependencies?.['flipper-plugin'],
   };
 }
 
@@ -83,6 +84,7 @@ async function getPluginDetailsV2(
     description: packageJson.description,
     category: packageJson.category,
     bugs: packageJson.bugs,
+    flipperSDKVersion: packageJson?.peerDependencies?.['flipper-plugin'],
   };
 }