TSK-1682: Introduced Schema module

[anotherpit]

For upcoming implementation of Recruit Script feature we need a way to:

• let one group of users compose and configure forms of typed fields
• let other groups of users fill those forms with their data

Think of something like Google Forms or Typeform. And also think of JSON schema as a comprehensive and standard language to describe forms.

So here I introduce Schema module which provides a set of context-agnostic building blocks to let any other Huly module incorporate forms built by one users and filled by others. The first module to utilize Schema will be Recruit, but this will happen in the next PR.

_{Huly®: UBERF-6413}

[aplatoff]

Just curious: why do not use platform's model for that? Is there any limitations and it can not cover some cases?