Miaz/schema name max length

[miazbikowski]

As per the requested check:

When a schema name exceeds 25 characters, show an error message otherwise will encounter:  AssetCloud::AssetNotSaved: Validation failed: Invalid schema: name is too long (max 25 characters)

from this list.

Added a simple maxLength to the section and theme block JSON schemas.

Tested locally with theme-tools debug:

Edit: what if we have a translation? can its key be more than 25 chars? this isn't the right approach