Add yarn generate to sg start web-standalone

Created by: oleggromov

Issue

1. Remove client/shared/src/graphql-operations.ts, which may be as well obsolete alongside with other files generated by yarn generate comand - which is usually the case
2. Run sg start web-standalone
3. See it complaining about the absense of this file

Test plan

1. Pull the branch
2. Remove the graphql-operations.ts file
3. Run sg start web-standalone
4. Ensure it works