Opt in deprecations docs

Fixes #3121

Fixes https://github.com/doctrine/dbal/issues/3114

Backporting #3088 into 2.7

Other drivers (including the cache) never supported fetch modes that are
not listed in `FetchMode`. Converting between the contants is only done
for PDO, so BC only needs to be restored here. PDO will validate the
fetch mode, we don’t have to.

Backporting #3095 into 2.7

Backporting #3085 into 2.7

Backporting #3083 into 2.7

Backporting #3089 into 2.7

Backporting #3090 into 2.7

It is required when using annotations to detect deprecation errors.

Backporting #3084 into 2.7

CS bump to 4.0, imports for global functions & constants

Add tests for column collation to prove it works

Allow dynamic intervals in DATE_ADD & DATE_SUB for SQLite

DateIntervalType (negative support) resolves doctrine/dbal#2578

Improve handling of schemas in SQL Server >= 2008

Drop PCRE x modifier in SqliteSchemaManager (#2885 rework)

Connection parameters are cached hashed

Start SQL Server using a synchronous command to avoid intermittent login failures