npm run typegen (and npm run build) now will check TypeScript errors.

I migrated jsconfig.json to tsconfig.json because tsc --build can only recognize tsconfig.json. tsc --build is faster than tsc because tsc --build has cache, so it's better to use tsc --build.

Since it reveals all typing errors now, I need to address all of them to make the build pass.

• Most of them are just missing types in configs, like the one below:

  this.config.image_token_index;
              ~~~~~~~~~~~~~~~~~
              ^ Property 'image_token_index' does not exist on type 'PretrainedConfig'.

  For those errors, I simply add @ts-expect-error comment to let TypeScript ignore it. I use @ts-expect-error instead of @ts-ignore because we can remove those comments once we add missing types in the future.

• I fixed some other types issues that I can fix.

• One thing I noticed is that MgpstrProcessor.batch_decode has different shape compared to the method in the parent class. This might not be a good idea.