sql: introduce type <XML>

[Totktonada]

Part of JDBC API.

[Korablev77]

Note that XML is not a part of ANSI SQL, it is rather user-defined type.

What is more, there is no native way to operate on XMLs in terms of Tarantool core. Still, we can simply store it as a string or blob.

[Totktonada]

My inderstanding is that SQLXML is Java pair of the XML type in SQL. The latter is described in Part 14 of the SQL standard 2011. But I think we can implement JDBC part on top of BLOB type and rewrite it when/if Tarantool will support XML type.

[Totktonada]

Now I found it is optional in JDBC.

[Totktonada]

It is optional in JDBC, so I think there is no reason to track it here. We have no enough demand to pay time to the feature, at least now. I think the issue can be closed. I'll close the linked tarantool-java issue.