Updated shop version to 4.8.8/5.1.8
ESDEV-2496 Fix subshop admin login issue oxUser::exists() fixes (cherry picked from commit 24992b5)

(cherry picked from commit 1ca031b1706a065a2348177a237c4827096ab5a5)

Conflicts:
	source/application/models/oxuser.php
ESDEV-2496 Fix subshop admin login issue oxUser::exists() fixes (cherry picked from commit 1d9b266) (cherry picked from commit 675093d)
ESDEV-2496 Fix subshop admin login issue Integration tests (cherry picked from commit 59611b9) (cherry picked from commit 551de71)
ESDEV-2496 Fix subshop admin login issue Integration tests (cherry picked from commit 3ab1183) (cherry picked from commit 6fce698)
ESDEV-2496 Fix subshop admin login issue Fixing multishop case, adding missing test for this case (cherry picked from commit 718f9b6) (cherry picked from commit 9ac57e4)
Fixed test: if plain password, it should be encoded. (cherry picked from commit b8d6e97)
#5753: Salt generation doesn't ensure the salt unpredictability.

Adding back handling of plaing password to oxUser::getPasswordHash(), as it is still used by ERP.
(cherry picked from commit 42d9af6)
(cherry picked from commit b007ffb)
#5753: Salt generation doesn't ensure the salt unpredictability.

Adding back handling of plaing password to oxUser::getPasswordHash(), as it is still used by ERP.
(cherry picked from commit 42d9af6)
(cherry picked from commit 9f241e1)