[CWEP002] properly handle serialization of computed relations
We now:
* have CWComputedRelation in the bootstrap schema to store computed relations
* properly serialize/deserialize it
* test first if the database has been migrated and contains the related table
Related to #3546717
[jcr: adjust unittest_querier to pass with the added entity type]
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception