Add scheme validation script

[ameshkov]

Additionally to the build script we should provide JSON scheme validation (for monitoring purposes).

• https://json-schema.org/
• https://www.npmjs.com/package/jsonschema

Here's what needs to be validated:

• filters.json (for every platform)
• filters_i18n.json (for every platform)
• number of filters in the filters.json (hardcode >= 80)

How it should work: node validate.js path_to_platforms_directory

[Mizzick]

Fixed