add @throws declarations to docs in Connection

Fix PSR2 rules : "the static declaration should come after visibility"

Fix Shard Manager docs with more accurate docblocks in `SQLAzureShardManager` and `PoolingShardManager`

In a few cases methods in Connection may throw a DBALException which
isn't declared in the docblock. As the Connection class is heavily
used by third party code, this code runs the risk of ignoring
those exceptions instead of handling them. While it is
technically not required to declare exceptions in PHP, it is highly
recommended, especially in public APIs.

[TASK] Fix articles of words sounding with a consonant

Fix PSR2 rules : "As per PSR2, the static declaration should come after the visibility declaration."

Close #2794

#2794 allowing `DateTimeImmutable` instances when converting in mutable date types - reverts unintentional BC break

#2794 adding tests verifying the regression, `DateTimeImmutable` should STILL work, even if unintentionally

Add all missing MariaDb keywords to MySQL

this check does not make sense

Stop using deprecated "json_array" type

fixed array declarations inside tools directory

AbstractMySQLDriver - Map 1429 to ConnectionException

Since it was deprecated.

Use short array declarations

fixed array declarations inside Query directory

Fix exception reference in documentation

Fixes #2760

As can be found in https://mariadb.com/kb/en/mariadb/reserved-words/.

Fix date interval database value truncation (string overflow)

Add mysql versions 5.6 and 5.7 to travis-ci

Fixes #2755
Fixes #2757

Fix documentation format regarding retryable exceptions