xblock-fields: Revert "Enforce type of the XBlocks Fields when set"

This reverts commit e08b98981e8b360f891f74cc5b17671e6ba9264c.
Enforce type of the XBlocks Fields when set

This updates the XBlock dependency to edX/XBlock@***
and add the newly introduced enforce_type methods
Add xmodule fields enforce_type tests
xblock-fields: Update hash of XBlock repository