Implement _meta.ts Type safe

[nikischin]

Is your feature request related to a problem? Please describe.
I would like to add type safety to _meta.ts just like for theme.config.tsx so I see if I typed the correct configurations.

Describe the solution you'd like
Add a type to the exported meta config object just like in the theme.config.tsx

Describe alternatives you've considered

Additional context
v3

[dimaMachina]

this kinda is improved in v4, because I did setup of parsing/normalizing _meta files on server, so in case you have a typo - you'll have a runtime error, but we can export MetaRecord type as well!

[nikischin]

this kinda is improved in v4, because I did setup of parsing/normalizing _meta files on server, so in case you have a typo - you'll have a runtime error, but we can export MetaRecord type as well!

Sounds like exporting MetaRecord would be an easy fix, even for v3? While I will love to migrate to v4 soon, I think for those still on v3 it would be helpful.