session.refresh() / load_on_ident() still hardwired to "deprecated" with_lockmode()

[Mike Bayer]

we deprecated with_lockmode() in 0.9 but session.refresh() still codes to it. linking refresh() to with_for_update() might be awkward due to the flags, probably have a dictionary passed in using kw argument with_for_update.

however, awkward to say session.refresh(obj, with_for_update={}) and that means FOR UPDATE since empty dict implies boolean false.

[Mike Bayer]

https://gerrit.sqlalchemy.org/403

[Mike Bayer]

Add with_for_update() support in session.refresh()

Session.refresh() is still hardcoded to legacy lockmode, come up with a new API so that the newer argument style works with it.

Added new argument :paramref:.with_for_update to the :meth:.Session.refresh method. When the :meth:.Query.with_lockmode method were deprecated in favor of :meth:.Query.with_for_update, the :meth:.Session.refresh method was never updated to reflect the new option.

Change-Id: Ia02a653746b7024699b515451525a88d7a17d63a Fixes: #3991

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