Make column-level collation quoting dialect-specific

Make column-level collation quoting dialect-specific

Fixed regression in 1.2 where newly repaired quoting
of collation names in :ticket:`3785` breaks SQL Server,
which explicitly does not understand a quoted collation
name.   Whether or not mixed-case collation names are
quoted or not is now deferred down to a dialect-level
decision so that each dialect can prepare these identifiers
directly.

Change-Id: Iaf0a8123d9bf4711219e320896bb28c5d2649304
Fixes: #4154