[repository] Drop type_and_source_from_eid and rename related cache
We don't want to handle anymore the entities.asource column so we shouldn't use
those anymore. Also rename repository's _type_source_cache into
_type_extid_cache as this is what it's containing now.
Do similar renaming to the system source API.
Related to #15538288
Tutorials
~~~~~~~~~
We present a few tutorials of different levels. The blog building
tutorial introduces one smoothly to the basic concepts.
Then there is a photo gallery construction tutorial which highlights
more advanced concepts such as unit tests, security settings,
migration scripts.
.. toctree::
:maxdepth: 1
base/index
advanced/index
tools/windmill.rst
textreports/index
dataimport/index