Rename ScanAllByPrimaryKey operator to ScanByPrimaryKey. Make the
LabelIndexExist function use the same functionality as PrimaryKeyExists
again, for now. Previously it was just returning false and before that
it used the same implementation as PrimaryKeyExist. The change to false
broke some existing e2e tests that relied on some label based indexing
operator being instantiated.
The query_v2_plan unit tests were needed in order to properly test if
the created logical plan of the new operator work properly. In order to
achieve this v2 versions of the several files were created, where the
old utilities were replaced with new ones, like query::v2 and
storage::v3. A new fake db accessor was also created in order to be able
to test the ScanAllByPrimaryKey operator.
