It is useful to save some customizations, preferences, or eve additions for test business templates
This feature is managed by a new class: ObjectPropertyTemplateItem

bt5_prototype: Add export functions for PathTempalteItem and BusinessPackage as well as make createInstallationData more efficient

As now, we expect our catalog object to be erp5 catalog and not indexable,
so its important to not reindex or unindex the old object.

Earlier, In ERP5Site, we use property 'isIndexable' to have control over indexing and unindexing.
This was usefull specially in case of bootstrap. To have this control, we had a function
`isIndexable` in SQLCatalog which we used to switch for enabling-disabling indexation. (769f9fb2)

Now, we do have ERP5 Catalog, which itself is an ERP5 Object, hence it has an accessor `isIndexable`
of itself which we plan to disable for now(as we don't want circular dependency while indexing
catalog in itself). But as we did have a function `isIndexable` in SQLCatalog which had control
over the indexing, we needed to rename this property for ERP5Site.

Hence, now we use property 'isIndexingRequired' for ERP5Site and use to have overall control
over indexing process.

Please note, we do not intend to change the same property name for any other object. Its just
for ERP5Site.

Required as most of the changes we have are in erp5_core and that's
why its important to install/update it before we install erp5_catalog_storage
bt5.