[4/n] [landing] move meta data into asset file

Summary: Move asset data into its own file

Test Plan: Make sure site still renders

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga, boristopalov

Differential Revision: https://phabricator.ashoat.com/D2554