Add missing input/output/dataset schemas to all templates

[patrikbraborec]

• Part of the Store schema cleanup push: input/output/dataset (or key-value-store) schemas are becoming a publication requirement, same mechanism as the README gate.
• More context: https://apify.slack.com/archives/C07240BTLR0/p1784212106821249

TBD:

• empty schema vs best effort example (such as historically used url input with apify.com default)