Replace JSON configs and configs generation with c12 config loader

[tysian]

Summary

Replace multiple json configs with single config file with c12 config loader.

Motivation

Using configs with json have some disadvantages, such as lack of type safety.
We can eliminate most config errors just by using defineConfig with full type support.
For runtime validation we can consider using Zod validation.

Most of the time we don't need to use more than one config, so single file config will be more than enough.

Goals

• deprecate config generating
• deprecate multiple configs
• replace json config with c12
• validate config using Zod