[SQL] Bump syntax version to 2

[jtojnar]

• My commit messages start with the package name in square brackets, e.g. [XML] .
• I have included new or enhanced syntax tests to cover the changes.
  this should be covered by the existing tests

To allow embedding it in version 2 syntaxes.

[deathaxe]

Well, it doesn't have any benefit beyond possibly breaking some 3rd-party packages.

To allow embedding it in version 2 syntaxes.

Just for the record. This statement is wrong.

v1 syntaxes can be included or embedded into v2 and vice versa without issues.

Version restrictions just exist for syntax inheritance. All syntaxes in an inheritance chain or diamond must be of same syntax version v1 or v2.

[jtojnar]

Closing in favour of using version: 1 in #4094.