[FEATURE] Provide a integrity check possibility (cli command, ...)

[sbuerk]

Fields can be reused, either by using the useExistingField option
or if prefix: false is used.

However, if two content blocks are defining incompatible field types
for a fieldname, this is not a proplem TCA or form-engine spoken. But
also ext_tables.sql structures are added using a hook. How would this
end up ?

For example, having for a field some_field a TCA Type check and for
another block TCA Type select with text values, that won't really
match. Who will win for the schema generation ?

Therfore, at least a cli command needs to be added to make a integrity
check in some way. contentblocks:integrity-check. Not sure, maybe this
can also start as a dedicated core command in ext:core with some events,
so content-block can provide custom checks to add/termine differences in
some way. Or at least start for content blocks.

This should be at least considert in the one or other way mid-term.