Add support for geometry/geography data types

[mp911de]

We should add support for SQL Server geometry/geography types that serialize and deserialize from/to Well-Known-Text/Well-Known-Binary representations and expose geometry/geography properties according to SQL Server specs.

See also:

• https://docs.microsoft.com/en-us/sql/connect/jdbc/use-spatial-datatypes?view=sql-server-2017

[mp911de]

See also ML discussion at https://groups.google.com/forum/#!topic/r2dbc/68aDbnAHDuw